diff --git a/Documentation/DocBook/drm.tmpl b/Documentation/DocBook/drm.tmpl
index 7df3134..c8c19a7 100644
--- a/Documentation/DocBook/drm.tmpl
+++ b/Documentation/DocBook/drm.tmpl
@@ -2338,6 +2338,12 @@ void intel_crt_init(struct drm_device *dev)
 !Edrivers/gpu/drm/drm_dp_helper.c
     </sect2>
     <sect2>
+      <title>Display Port MST Helper Functions Reference</title>
+!Pdrivers/gpu/drm/drm_dp_mst_topology.c dp mst helper
+!Iinclude/drm/drm_dp_mst_helper.h
+!Edrivers/gpu/drm/drm_dp_mst_topology.c
+    </sect2>
+    <sect2>
       <title>EDID Helper Functions Reference</title>
 !Edrivers/gpu/drm/drm_edid.c
     </sect2>
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index dd2ba42..af9a609 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -24,7 +24,7 @@ drm-$(CONFIG_DRM_PANEL) += drm_panel.o
 drm-usb-y   := drm_usb.o
 
 drm_kms_helper-y := drm_crtc_helper.o drm_dp_helper.o drm_probe_helper.o \
-		drm_plane_helper.o
+		drm_plane_helper.o drm_dp_mst_topology.o
 drm_kms_helper-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
 drm_kms_helper-$(CONFIG_DRM_KMS_FB_HELPER) += drm_fb_helper.o
 drm_kms_helper-$(CONFIG_DRM_KMS_CMA_HELPER) += drm_fb_cma_helper.o
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
new file mode 100644
index 0000000..73bc773
--- /dev/null
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -0,0 +1,2712 @@
+/*
+ * Copyright © 2014 Red Hat
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/i2c.h>
+#include <drm/drm_dp_mst_helper.h>
+#include <drm/drmP.h>
+
+#include <drm/drm_fixed.h>
+
+/**
+ * DOC: dp mst helper
+ *
+ * These functions contain parts of the DisplayPort 1.2a MultiStream Transport
+ * protocol. The helpers contain a topology manager and bandwidth manager.
+ * The helpers encapsulate the sending and received of sideband msgs.
+ */
+static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
+				  char *buf);
+static int test_calc_pbn_mode(void);
+
+static void drm_dp_put_port(struct drm_dp_mst_port *port);
+
+static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
+				     int id,
+				     struct drm_dp_payload *payload);
+
+static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
+				  struct drm_dp_mst_port *port,
+				  int offset, int size, u8 *bytes);
+
+static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
+				    struct drm_dp_mst_branch *mstb);
+static int drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
+					   struct drm_dp_mst_branch *mstb,
+					   struct drm_dp_mst_port *port);
+static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
+				 u8 *guid);
+
+static int drm_dp_mst_register_i2c_bus(struct drm_dp_aux *aux);
+static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_aux *aux);
+static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr);
+/* sideband msg handling */
+static u8 drm_dp_msg_header_crc4(const uint8_t *data, size_t num_nibbles)
+{
+	u8 bitmask = 0x80;
+	u8 bitshift = 7;
+	u8 array_index = 0;
+	int number_of_bits = num_nibbles * 4;
+	u8 remainder = 0;
+
+	while (number_of_bits != 0) {
+		number_of_bits--;
+		remainder <<= 1;
+		remainder |= (data[array_index] & bitmask) >> bitshift;
+		bitmask >>= 1;
+		bitshift--;
+		if (bitmask == 0) {
+			bitmask = 0x80;
+			bitshift = 7;
+			array_index++;
+		}
+		if ((remainder & 0x10) == 0x10)
+			remainder ^= 0x13;
+	}
+
+	number_of_bits = 4;
+	while (number_of_bits != 0) {
+		number_of_bits--;
+		remainder <<= 1;
+		if ((remainder & 0x10) != 0)
+			remainder ^= 0x13;
+	}
+
+	return remainder;
+}
+
+static u8 drm_dp_msg_data_crc4(const uint8_t *data, u8 number_of_bytes)
+{
+	u8 bitmask = 0x80;
+	u8 bitshift = 7;
+	u8 array_index = 0;
+	int number_of_bits = number_of_bytes * 8;
+	u16 remainder = 0;
+
+	while (number_of_bits != 0) {
+		number_of_bits--;
+		remainder <<= 1;
+		remainder |= (data[array_index] & bitmask) >> bitshift;
+		bitmask >>= 1;
+		bitshift--;
+		if (bitmask == 0) {
+			bitmask = 0x80;
+			bitshift = 7;
+			array_index++;
+		}
+		if ((remainder & 0x100) == 0x100)
+			remainder ^= 0xd5;
+	}
+
+	number_of_bits = 8;
+	while (number_of_bits != 0) {
+		number_of_bits--;
+		remainder <<= 1;
+		if ((remainder & 0x100) != 0)
+			remainder ^= 0xd5;
+	}
+
+	return remainder & 0xff;
+}
+static inline u8 drm_dp_calc_sb_hdr_size(struct drm_dp_sideband_msg_hdr *hdr)
+{
+	u8 size = 3;
+	size += (hdr->lct / 2);
+	return size;
+}
+
+static void drm_dp_encode_sideband_msg_hdr(struct drm_dp_sideband_msg_hdr *hdr,
+					   u8 *buf, int *len)
+{
+	int idx = 0;
+	int i;
+	u8 crc4;
+	buf[idx++] = ((hdr->lct & 0xf) << 4) | (hdr->lcr & 0xf);
+	for (i = 0; i < (hdr->lct / 2); i++)
+		buf[idx++] = hdr->rad[i];
+	buf[idx++] = (hdr->broadcast << 7) | (hdr->path_msg << 6) |
+		(hdr->msg_len & 0x3f);
+	buf[idx++] = (hdr->somt << 7) | (hdr->eomt << 6) | (hdr->seqno << 4);
+
+	crc4 = drm_dp_msg_header_crc4(buf, (idx * 2) - 1);
+	buf[idx - 1] |= (crc4 & 0xf);
+
+	*len = idx;
+}
+
+static bool drm_dp_decode_sideband_msg_hdr(struct drm_dp_sideband_msg_hdr *hdr,
+					   u8 *buf, int buflen, u8 *hdrlen)
+{
+	u8 crc4;
+	u8 len;
+	int i;
+	u8 idx;
+	if (buf[0] == 0)
+		return false;
+	len = 3;
+	len += ((buf[0] & 0xf0) >> 4) / 2;
+	if (len > buflen)
+		return false;
+	crc4 = drm_dp_msg_header_crc4(buf, (len * 2) - 1);
+
+	if ((crc4 & 0xf) != (buf[len - 1] & 0xf)) {
+		DRM_DEBUG_KMS("crc4 mismatch 0x%x 0x%x\n", crc4, buf[len - 1]);
+		return false;
+	}
+
+	hdr->lct = (buf[0] & 0xf0) >> 4;
+	hdr->lcr = (buf[0] & 0xf);
+	idx = 1;
+	for (i = 0; i < (hdr->lct / 2); i++)
+		hdr->rad[i] = buf[idx++];
+	hdr->broadcast = (buf[idx] >> 7) & 0x1;
+	hdr->path_msg = (buf[idx] >> 6) & 0x1;
+	hdr->msg_len = buf[idx] & 0x3f;
+	idx++;
+	hdr->somt = (buf[idx] >> 7) & 0x1;
+	hdr->eomt = (buf[idx] >> 6) & 0x1;
+	hdr->seqno = (buf[idx] >> 4) & 0x1;
+	idx++;
+	*hdrlen = idx;
+	return true;
+}
+
+static void drm_dp_encode_sideband_req(struct drm_dp_sideband_msg_req_body *req,
+				       struct drm_dp_sideband_msg_tx *raw)
+{
+	int idx = 0;
+	int i;
+	u8 *buf = raw->msg;
+	buf[idx++] = req->req_type & 0x7f;
+
+	switch (req->req_type) {
+	case DP_ENUM_PATH_RESOURCES:
+		buf[idx] = (req->u.port_num.port_number & 0xf) << 4;
+		idx++;
+		break;
+	case DP_ALLOCATE_PAYLOAD:
+		buf[idx] = (req->u.allocate_payload.port_number & 0xf) << 4 |
+			(req->u.allocate_payload.number_sdp_streams & 0xf);
+		idx++;
+		buf[idx] = (req->u.allocate_payload.vcpi & 0x7f);
+		idx++;
+		buf[idx] = (req->u.allocate_payload.pbn >> 8);
+		idx++;
+		buf[idx] = (req->u.allocate_payload.pbn & 0xff);
+		idx++;
+		for (i = 0; i < req->u.allocate_payload.number_sdp_streams / 2; i++) {
+			buf[idx] = ((req->u.allocate_payload.sdp_stream_sink[i * 2] & 0xf) << 4) |
+				(req->u.allocate_payload.sdp_stream_sink[i * 2 + 1] & 0xf);
+			idx++;
+		}
+		if (req->u.allocate_payload.number_sdp_streams & 1) {
+			i = req->u.allocate_payload.number_sdp_streams - 1;
+			buf[idx] = (req->u.allocate_payload.sdp_stream_sink[i] & 0xf) << 4;
+			idx++;
+		}
+		break;
+	case DP_QUERY_PAYLOAD:
+		buf[idx] = (req->u.query_payload.port_number & 0xf) << 4;
+		idx++;
+		buf[idx] = (req->u.query_payload.vcpi & 0x7f);
+		idx++;
+		break;
+	case DP_REMOTE_DPCD_READ:
+		buf[idx] = (req->u.dpcd_read.port_number & 0xf) << 4;
+		buf[idx] |= ((req->u.dpcd_read.dpcd_address & 0xf0000) >> 16) & 0xf;
+		idx++;
+		buf[idx] = (req->u.dpcd_read.dpcd_address & 0xff00) >> 8;
+		idx++;
+		buf[idx] = (req->u.dpcd_read.dpcd_address & 0xff);
+		idx++;
+		buf[idx] = (req->u.dpcd_read.num_bytes);
+		idx++;
+		break;
+
+	case DP_REMOTE_DPCD_WRITE:
+		buf[idx] = (req->u.dpcd_write.port_number & 0xf) << 4;
+		buf[idx] |= ((req->u.dpcd_write.dpcd_address & 0xf0000) >> 16) & 0xf;
+		idx++;
+		buf[idx] = (req->u.dpcd_write.dpcd_address & 0xff00) >> 8;
+		idx++;
+		buf[idx] = (req->u.dpcd_write.dpcd_address & 0xff);
+		idx++;
+		buf[idx] = (req->u.dpcd_write.num_bytes);
+		idx++;
+		memcpy(&buf[idx], req->u.dpcd_write.bytes, req->u.dpcd_write.num_bytes);
+		idx += req->u.dpcd_write.num_bytes;
+		break;
+	case DP_REMOTE_I2C_READ:
+		buf[idx] = (req->u.i2c_read.port_number & 0xf) << 4;
+		buf[idx] |= (req->u.i2c_read.num_transactions & 0x3);
+		idx++;
+		for (i = 0; i < (req->u.i2c_read.num_transactions & 0x3); i++) {
+			buf[idx] = req->u.i2c_read.transactions[i].i2c_dev_id & 0x7f;
+			idx++;
+			buf[idx] = req->u.i2c_read.transactions[i].num_bytes;
+			idx++;
+			memcpy(&buf[idx], req->u.i2c_read.transactions[i].bytes, req->u.i2c_read.transactions[i].num_bytes);
+			idx += req->u.i2c_read.transactions[i].num_bytes;
+
+			buf[idx] = (req->u.i2c_read.transactions[i].no_stop_bit & 0x1) << 5;
+			buf[idx] |= (req->u.i2c_read.transactions[i].i2c_transaction_delay & 0xf);
+			idx++;
+		}
+		buf[idx] = (req->u.i2c_read.read_i2c_device_id) & 0x7f;
+		idx++;
+		buf[idx] = (req->u.i2c_read.num_bytes_read);
+		idx++;
+		break;
+
+	case DP_REMOTE_I2C_WRITE:
+		buf[idx] = (req->u.i2c_write.port_number & 0xf) << 4;
+		idx++;
+		buf[idx] = (req->u.i2c_write.write_i2c_device_id) & 0x7f;
+		idx++;
+		buf[idx] = (req->u.i2c_write.num_bytes);
+		idx++;
+		memcpy(&buf[idx], req->u.i2c_write.bytes, req->u.i2c_write.num_bytes);
+		idx += req->u.i2c_write.num_bytes;
+		break;
+	}
+	raw->cur_len = idx;
+}
+
+static void drm_dp_crc_sideband_chunk_req(u8 *msg, u8 len)
+{
+	u8 crc4;
+	crc4 = drm_dp_msg_data_crc4(msg, len);
+	msg[len] = crc4;
+}
+
+static void drm_dp_encode_sideband_reply(struct drm_dp_sideband_msg_reply_body *rep,
+					 struct drm_dp_sideband_msg_tx *raw)
+{
+	int idx = 0;
+	u8 *buf = raw->msg;
+
+	buf[idx++] = (rep->reply_type & 0x1) << 7 | (rep->req_type & 0x7f);
+
+	raw->cur_len = idx;
+}
+
+/* this adds a chunk of msg to the builder to get the final msg */
+static bool drm_dp_sideband_msg_build(struct drm_dp_sideband_msg_rx *msg,
+				      u8 *replybuf, u8 replybuflen, bool hdr)
+{
+	int ret;
+	u8 crc4;
+
+	if (hdr) {
+		u8 hdrlen;
+		struct drm_dp_sideband_msg_hdr recv_hdr;
+		ret = drm_dp_decode_sideband_msg_hdr(&recv_hdr, replybuf, replybuflen, &hdrlen);
+		if (ret == false) {
+			print_hex_dump(KERN_DEBUG, "failed hdr", DUMP_PREFIX_NONE, 16, 1, replybuf, replybuflen, false);
+			return false;
+		}
+
+		/* get length contained in this portion */
+		msg->curchunk_len = recv_hdr.msg_len;
+		msg->curchunk_hdrlen = hdrlen;
+
+		/* we have already gotten an somt - don't bother parsing */
+		if (recv_hdr.somt && msg->have_somt)
+			return false;
+
+		if (recv_hdr.somt) {
+			memcpy(&msg->initial_hdr, &recv_hdr, sizeof(struct drm_dp_sideband_msg_hdr));
+			msg->have_somt = true;
+		}
+		if (recv_hdr.eomt)
+			msg->have_eomt = true;
+
+		/* copy the bytes for the remainder of this header chunk */
+		msg->curchunk_idx = min(msg->curchunk_len, (u8)(replybuflen - hdrlen));
+		memcpy(&msg->chunk[0], replybuf + hdrlen, msg->curchunk_idx);
+	} else {
+		memcpy(&msg->chunk[msg->curchunk_idx], replybuf, replybuflen);
+		msg->curchunk_idx += replybuflen;
+	}
+
+	if (msg->curchunk_idx >= msg->curchunk_len) {
+		/* do CRC */
+		crc4 = drm_dp_msg_data_crc4(msg->chunk, msg->curchunk_len - 1);
+		/* copy chunk into bigger msg */
+		memcpy(&msg->msg[msg->curlen], msg->chunk, msg->curchunk_len - 1);
+		msg->curlen += msg->curchunk_len - 1;
+	}
+	return true;
+}
+
+static bool drm_dp_sideband_parse_link_address(struct drm_dp_sideband_msg_rx *raw,
+					       struct drm_dp_sideband_msg_reply_body *repmsg)
+{
+	int idx = 1;
+	int i;
+	memcpy(repmsg->u.link_addr.guid, &raw->msg[idx], 16);
+	idx += 16;
+	repmsg->u.link_addr.nports = raw->msg[idx] & 0xf;
+	idx++;
+	if (idx > raw->curlen)
+		goto fail_len;
+	for (i = 0; i < repmsg->u.link_addr.nports; i++) {
+		if (raw->msg[idx] & 0x80)
+			repmsg->u.link_addr.ports[i].input_port = 1;
+
+		repmsg->u.link_addr.ports[i].peer_device_type = (raw->msg[idx] >> 4) & 0x7;
+		repmsg->u.link_addr.ports[i].port_number = (raw->msg[idx] & 0xf);
+
+		idx++;
+		if (idx > raw->curlen)
+			goto fail_len;
+		repmsg->u.link_addr.ports[i].mcs = (raw->msg[idx] >> 7) & 0x1;
+		repmsg->u.link_addr.ports[i].ddps = (raw->msg[idx] >> 6) & 0x1;
+		if (repmsg->u.link_addr.ports[i].input_port == 0)
+			repmsg->u.link_addr.ports[i].legacy_device_plug_status = (raw->msg[idx] >> 5) & 0x1;
+		idx++;
+		if (idx > raw->curlen)
+			goto fail_len;
+		if (repmsg->u.link_addr.ports[i].input_port == 0) {
+			repmsg->u.link_addr.ports[i].dpcd_revision = (raw->msg[idx]);
+			idx++;
+			if (idx > raw->curlen)
+				goto fail_len;
+			memcpy(repmsg->u.link_addr.ports[i].peer_guid, &raw->msg[idx], 16);
+			idx += 16;
+			if (idx > raw->curlen)
+				goto fail_len;
+			repmsg->u.link_addr.ports[i].num_sdp_streams = (raw->msg[idx] >> 4) & 0xf;
+			repmsg->u.link_addr.ports[i].num_sdp_stream_sinks = (raw->msg[idx] & 0xf);
+			idx++;
+
+		}
+		if (idx > raw->curlen)
+			goto fail_len;
+	}
+
+	return true;
+fail_len:
+	DRM_DEBUG_KMS("link address reply parse length fail %d %d\n", idx, raw->curlen);
+	return false;
+}
+
+static bool drm_dp_sideband_parse_remote_dpcd_read(struct drm_dp_sideband_msg_rx *raw,
+						   struct drm_dp_sideband_msg_reply_body *repmsg)
+{
+	int idx = 1;
+	repmsg->u.remote_dpcd_read_ack.port_number = raw->msg[idx] & 0xf;
+	idx++;
+	if (idx > raw->curlen)
+		goto fail_len;
+	repmsg->u.remote_dpcd_read_ack.num_bytes = raw->msg[idx];
+	if (idx > raw->curlen)
+		goto fail_len;
+
+	memcpy(repmsg->u.remote_dpcd_read_ack.bytes, &raw->msg[idx], repmsg->u.remote_dpcd_read_ack.num_bytes);
+	return true;
+fail_len:
+	DRM_DEBUG_KMS("link address reply parse length fail %d %d\n", idx, raw->curlen);
+	return false;
+}
+
+static bool drm_dp_sideband_parse_remote_dpcd_write(struct drm_dp_sideband_msg_rx *raw,
+						      struct drm_dp_sideband_msg_reply_body *repmsg)
+{
+	int idx = 1;
+	repmsg->u.remote_dpcd_write_ack.port_number = raw->msg[idx] & 0xf;
+	idx++;
+	if (idx > raw->curlen)
+		goto fail_len;
+	return true;
+fail_len:
+	DRM_DEBUG_KMS("parse length fail %d %d\n", idx, raw->curlen);
+	return false;
+}
+
+static bool drm_dp_sideband_parse_remote_i2c_read_ack(struct drm_dp_sideband_msg_rx *raw,
+						      struct drm_dp_sideband_msg_reply_body *repmsg)
+{
+	int idx = 1;
+
+	repmsg->u.remote_i2c_read_ack.port_number = (raw->msg[idx] & 0xf);
+	idx++;
+	if (idx > raw->curlen)
+		goto fail_len;
+	repmsg->u.remote_i2c_read_ack.num_bytes = raw->msg[idx];
+	idx++;
+	/* TODO check */
+	memcpy(repmsg->u.remote_i2c_read_ack.bytes, &raw->msg[idx], repmsg->u.remote_i2c_read_ack.num_bytes);
+	return true;
+fail_len:
+	DRM_DEBUG_KMS("remote i2c reply parse length fail %d %d\n", idx, raw->curlen);
+	return false;
+}
+
+static bool drm_dp_sideband_parse_enum_path_resources_ack(struct drm_dp_sideband_msg_rx *raw,
+							  struct drm_dp_sideband_msg_reply_body *repmsg)
+{
+	int idx = 1;
+	repmsg->u.path_resources.port_number = (raw->msg[idx] >> 4) & 0xf;
+	idx++;
+	if (idx > raw->curlen)
+		goto fail_len;
+	repmsg->u.path_resources.full_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
+	idx += 2;
+	if (idx > raw->curlen)
+		goto fail_len;
+	repmsg->u.path_resources.avail_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
+	idx += 2;
+	if (idx > raw->curlen)
+		goto fail_len;
+	return true;
+fail_len:
+	DRM_DEBUG_KMS("enum resource parse length fail %d %d\n", idx, raw->curlen);
+	return false;
+}
+
+static bool drm_dp_sideband_parse_allocate_payload_ack(struct drm_dp_sideband_msg_rx *raw,
+							  struct drm_dp_sideband_msg_reply_body *repmsg)
+{
+	int idx = 1;
+	repmsg->u.allocate_payload.port_number = (raw->msg[idx] >> 4) & 0xf;
+	idx++;
+	if (idx > raw->curlen)
+		goto fail_len;
+	repmsg->u.allocate_payload.vcpi = raw->msg[idx];
+	idx++;
+	if (idx > raw->curlen)
+		goto fail_len;
+	repmsg->u.allocate_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
+	idx += 2;
+	if (idx > raw->curlen)
+		goto fail_len;
+	return true;
+fail_len:
+	DRM_DEBUG_KMS("allocate payload parse length fail %d %d\n", idx, raw->curlen);
+	return false;
+}
+
+static bool drm_dp_sideband_parse_query_payload_ack(struct drm_dp_sideband_msg_rx *raw,
+						    struct drm_dp_sideband_msg_reply_body *repmsg)
+{
+	int idx = 1;
+	repmsg->u.query_payload.port_number = (raw->msg[idx] >> 4) & 0xf;
+	idx++;
+	if (idx > raw->curlen)
+		goto fail_len;
+	repmsg->u.query_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]);
+	idx += 2;
+	if (idx > raw->curlen)
+		goto fail_len;
+	return true;
+fail_len:
+	DRM_DEBUG_KMS("query payload parse length fail %d %d\n", idx, raw->curlen);
+	return false;
+}
+
+static bool drm_dp_sideband_parse_reply(struct drm_dp_sideband_msg_rx *raw,
+					struct drm_dp_sideband_msg_reply_body *msg)
+{
+	memset(msg, 0, sizeof(*msg));
+	msg->reply_type = (raw->msg[0] & 0x80) >> 7;
+	msg->req_type = (raw->msg[0] & 0x7f);
+
+	if (msg->reply_type) {
+		memcpy(msg->u.nak.guid, &raw->msg[1], 16);
+		msg->u.nak.reason = raw->msg[17];
+		msg->u.nak.nak_data = raw->msg[18];
+		return false;
+	}
+
+	switch (msg->req_type) {
+	case DP_LINK_ADDRESS:
+		return drm_dp_sideband_parse_link_address(raw, msg);
+	case DP_QUERY_PAYLOAD:
+		return drm_dp_sideband_parse_query_payload_ack(raw, msg);
+	case DP_REMOTE_DPCD_READ:
+		return drm_dp_sideband_parse_remote_dpcd_read(raw, msg);
+	case DP_REMOTE_DPCD_WRITE:
+		return drm_dp_sideband_parse_remote_dpcd_write(raw, msg);
+	case DP_REMOTE_I2C_READ:
+		return drm_dp_sideband_parse_remote_i2c_read_ack(raw, msg);
+	case DP_ENUM_PATH_RESOURCES:
+		return drm_dp_sideband_parse_enum_path_resources_ack(raw, msg);
+	case DP_ALLOCATE_PAYLOAD:
+		return drm_dp_sideband_parse_allocate_payload_ack(raw, msg);
+	default:
+		DRM_ERROR("Got unknown reply 0x%02x\n", msg->req_type);
+		return false;
+	}
+}
+
+static bool drm_dp_sideband_parse_connection_status_notify(struct drm_dp_sideband_msg_rx *raw,
+							   struct drm_dp_sideband_msg_req_body *msg)
+{
+	int idx = 1;
+
+	msg->u.conn_stat.port_number = (raw->msg[idx] & 0xf0) >> 4;
+	idx++;
+	if (idx > raw->curlen)
+		goto fail_len;
+
+	memcpy(msg->u.conn_stat.guid, &raw->msg[idx], 16);
+	idx += 16;
+	if (idx > raw->curlen)
+		goto fail_len;
+
+	msg->u.conn_stat.legacy_device_plug_status = (raw->msg[idx] >> 6) & 0x1;
+	msg->u.conn_stat.displayport_device_plug_status = (raw->msg[idx] >> 5) & 0x1;
+	msg->u.conn_stat.message_capability_status = (raw->msg[idx] >> 4) & 0x1;
+	msg->u.conn_stat.input_port = (raw->msg[idx] >> 3) & 0x1;
+	msg->u.conn_stat.peer_device_type = (raw->msg[idx] & 0x7);
+	idx++;
+	return true;
+fail_len:
+	DRM_DEBUG_KMS("connection status reply parse length fail %d %d\n", idx, raw->curlen);
+	return false;
+}
+
+static bool drm_dp_sideband_parse_resource_status_notify(struct drm_dp_sideband_msg_rx *raw,
+							   struct drm_dp_sideband_msg_req_body *msg)
+{
+	int idx = 1;
+
+	msg->u.resource_stat.port_number = (raw->msg[idx] & 0xf0) >> 4;
+	idx++;
+	if (idx > raw->curlen)
+		goto fail_len;
+
+	memcpy(msg->u.resource_stat.guid, &raw->msg[idx], 16);
+	idx += 16;
+	if (idx > raw->curlen)
+		goto fail_len;
+
+	msg->u.resource_stat.available_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]);
+	idx++;
+	return true;
+fail_len:
+	DRM_DEBUG_KMS("resource status reply parse length fail %d %d\n", idx, raw->curlen);
+	return false;
+}
+
+static bool drm_dp_sideband_parse_req(struct drm_dp_sideband_msg_rx *raw,
+				      struct drm_dp_sideband_msg_req_body *msg)
+{
+	memset(msg, 0, sizeof(*msg));
+	msg->req_type = (raw->msg[0] & 0x7f);
+
+	switch (msg->req_type) {
+	case DP_CONNECTION_STATUS_NOTIFY:
+		return drm_dp_sideband_parse_connection_status_notify(raw, msg);
+	case DP_RESOURCE_STATUS_NOTIFY:
+		return drm_dp_sideband_parse_resource_status_notify(raw, msg);
+	default:
+		DRM_ERROR("Got unknown request 0x%02x\n", msg->req_type);
+		return false;
+	}
+}
+
+static int build_dpcd_write(struct drm_dp_sideband_msg_tx *msg, u8 port_num, u32 offset, u8 num_bytes, u8 *bytes)
+{
+	struct drm_dp_sideband_msg_req_body req;
+
+	req.req_type = DP_REMOTE_DPCD_WRITE;
+	req.u.dpcd_write.port_number = port_num;
+	req.u.dpcd_write.dpcd_address = offset;
+	req.u.dpcd_write.num_bytes = num_bytes;
+	req.u.dpcd_write.bytes = bytes;
+	drm_dp_encode_sideband_req(&req, msg);
+
+	return 0;
+}
+
+static int build_link_address(struct drm_dp_sideband_msg_tx *msg)
+{
+	struct drm_dp_sideband_msg_req_body req;
+
+	req.req_type = DP_LINK_ADDRESS;
+	drm_dp_encode_sideband_req(&req, msg);
+	return 0;
+}
+
+static int build_enum_path_resources(struct drm_dp_sideband_msg_tx *msg, int port_num)
+{
+	struct drm_dp_sideband_msg_req_body req;
+
+	req.req_type = DP_ENUM_PATH_RESOURCES;
+	req.u.port_num.port_number = port_num;
+	drm_dp_encode_sideband_req(&req, msg);
+	msg->path_msg = true;
+	return 0;
+}
+
+static int build_allocate_payload(struct drm_dp_sideband_msg_tx *msg, int port_num,
+				  u8 vcpi, uint16_t pbn)
+{
+	struct drm_dp_sideband_msg_req_body req;
+	memset(&req, 0, sizeof(req));
+	req.req_type = DP_ALLOCATE_PAYLOAD;
+	req.u.allocate_payload.port_number = port_num;
+	req.u.allocate_payload.vcpi = vcpi;
+	req.u.allocate_payload.pbn = pbn;
+	drm_dp_encode_sideband_req(&req, msg);
+	msg->path_msg = true;
+	return 0;
+}
+
+static int drm_dp_mst_assign_payload_id(struct drm_dp_mst_topology_mgr *mgr,
+					struct drm_dp_vcpi *vcpi)
+{
+	int ret;
+
+	mutex_lock(&mgr->payload_lock);
+	ret = find_first_zero_bit(&mgr->payload_mask, mgr->max_payloads + 1);
+	if (ret > mgr->max_payloads) {
+		ret = -EINVAL;
+		DRM_DEBUG_KMS("out of payload ids %d\n", ret);
+		goto out_unlock;
+	}
+
+	set_bit(ret, &mgr->payload_mask);
+	vcpi->vcpi = ret;
+	mgr->proposed_vcpis[ret - 1] = vcpi;
+out_unlock:
+	mutex_unlock(&mgr->payload_lock);
+	return ret;
+}
+
+static void drm_dp_mst_put_payload_id(struct drm_dp_mst_topology_mgr *mgr,
+				      int id)
+{
+	if (id == 0)
+		return;
+
+	mutex_lock(&mgr->payload_lock);
+	DRM_DEBUG_KMS("putting payload %d\n", id);
+	clear_bit(id, &mgr->payload_mask);
+	mgr->proposed_vcpis[id - 1] = NULL;
+	mutex_unlock(&mgr->payload_lock);
+}
+
+static bool check_txmsg_state(struct drm_dp_mst_topology_mgr *mgr,
+			      struct drm_dp_sideband_msg_tx *txmsg)
+{
+	bool ret;
+	mutex_lock(&mgr->qlock);
+	ret = (txmsg->state == DRM_DP_SIDEBAND_TX_RX ||
+	       txmsg->state == DRM_DP_SIDEBAND_TX_TIMEOUT);
+	mutex_unlock(&mgr->qlock);
+	return ret;
+}
+
+static int drm_dp_mst_wait_tx_reply(struct drm_dp_mst_branch *mstb,
+				    struct drm_dp_sideband_msg_tx *txmsg)
+{
+	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
+	int ret;
+
+	ret = wait_event_timeout(mgr->tx_waitq,
+				 check_txmsg_state(mgr, txmsg),
+				 (4 * HZ));
+	mutex_lock(&mstb->mgr->qlock);
+	if (ret > 0) {
+		if (txmsg->state == DRM_DP_SIDEBAND_TX_TIMEOUT) {
+			ret = -EIO;
+			goto out;
+		}
+	} else {
+		DRM_DEBUG_KMS("timedout msg send %p %d %d\n", txmsg, txmsg->state, txmsg->seqno);
+
+		/* dump some state */
+		ret = -EIO;
+
+		/* remove from q */
+		if (txmsg->state == DRM_DP_SIDEBAND_TX_QUEUED ||
+		    txmsg->state == DRM_DP_SIDEBAND_TX_START_SEND) {
+			list_del(&txmsg->next);
+		}
+
+		if (txmsg->state == DRM_DP_SIDEBAND_TX_START_SEND ||
+		    txmsg->state == DRM_DP_SIDEBAND_TX_SENT) {
+			mstb->tx_slots[txmsg->seqno] = NULL;
+		}
+	}
+out:
+	mutex_unlock(&mgr->qlock);
+
+	return ret;
+}
+
+static struct drm_dp_mst_branch *drm_dp_add_mst_branch_device(u8 lct, u8 *rad)
+{
+	struct drm_dp_mst_branch *mstb;
+
+	mstb = kzalloc(sizeof(*mstb), GFP_KERNEL);
+	if (!mstb)
+		return NULL;
+
+	mstb->lct = lct;
+	if (lct > 1)
+		memcpy(mstb->rad, rad, lct / 2);
+	INIT_LIST_HEAD(&mstb->ports);
+	kref_init(&mstb->kref);
+	return mstb;
+}
+
+static void drm_dp_destroy_mst_branch_device(struct kref *kref)
+{
+	struct drm_dp_mst_branch *mstb = container_of(kref, struct drm_dp_mst_branch, kref);
+	struct drm_dp_mst_port *port, *tmp;
+	bool wake_tx = false;
+
+	cancel_work_sync(&mstb->mgr->work);
+
+	/*
+	 * destroy all ports - don't need lock
+	 * as there are no more references to the mst branch
+	 * device at this point.
+	 */
+	list_for_each_entry_safe(port, tmp, &mstb->ports, next) {
+		list_del(&port->next);
+		drm_dp_put_port(port);
+	}
+
+	/* drop any tx slots msg */
+	mutex_lock(&mstb->mgr->qlock);
+	if (mstb->tx_slots[0]) {
+		mstb->tx_slots[0]->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
+		mstb->tx_slots[0] = NULL;
+		wake_tx = true;
+	}
+	if (mstb->tx_slots[1]) {
+		mstb->tx_slots[1]->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
+		mstb->tx_slots[1] = NULL;
+		wake_tx = true;
+	}
+	mutex_unlock(&mstb->mgr->qlock);
+
+	if (wake_tx)
+		wake_up(&mstb->mgr->tx_waitq);
+	kfree(mstb);
+}
+
+static void drm_dp_put_mst_branch_device(struct drm_dp_mst_branch *mstb)
+{
+	kref_put(&mstb->kref, drm_dp_destroy_mst_branch_device);
+}
+
+
+static void drm_dp_port_teardown_pdt(struct drm_dp_mst_port *port, int old_pdt)
+{
+	switch (old_pdt) {
+	case DP_PEER_DEVICE_DP_LEGACY_CONV:
+	case DP_PEER_DEVICE_SST_SINK:
+		/* remove i2c over sideband */
+		drm_dp_mst_unregister_i2c_bus(&port->aux);
+		break;
+	case DP_PEER_DEVICE_MST_BRANCHING:
+		drm_dp_put_mst_branch_device(port->mstb);
+		port->mstb = NULL;
+		break;
+	}
+}
+
+static void drm_dp_destroy_port(struct kref *kref)
+{
+	struct drm_dp_mst_port *port = container_of(kref, struct drm_dp_mst_port, kref);
+	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
+	if (!port->input) {
+		port->vcpi.num_slots = 0;
+		if (port->connector)
+			(*port->mgr->cbs->destroy_connector)(mgr, port->connector);
+		drm_dp_port_teardown_pdt(port, port->pdt);
+
+		if (!port->input && port->vcpi.vcpi > 0)
+			drm_dp_mst_put_payload_id(mgr, port->vcpi.vcpi);
+	}
+	kfree(port);
+
+	(*mgr->cbs->hotplug)(mgr);
+}
+
+static void drm_dp_put_port(struct drm_dp_mst_port *port)
+{
+	kref_put(&port->kref, drm_dp_destroy_port);
+}
+
+static struct drm_dp_mst_branch *drm_dp_mst_get_validated_mstb_ref_locked(struct drm_dp_mst_branch *mstb, struct drm_dp_mst_branch *to_find)
+{
+	struct drm_dp_mst_port *port;
+	struct drm_dp_mst_branch *rmstb;
+	if (to_find == mstb) {
+		kref_get(&mstb->kref);
+		return mstb;
+	}
+	list_for_each_entry(port, &mstb->ports, next) {
+		if (port->mstb) {
+			rmstb = drm_dp_mst_get_validated_mstb_ref_locked(port->mstb, to_find);
+			if (rmstb)
+				return rmstb;
+		}
+	}
+	return NULL;
+}
+
+static struct drm_dp_mst_branch *drm_dp_get_validated_mstb_ref(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_branch *mstb)
+{
+	struct drm_dp_mst_branch *rmstb = NULL;
+	mutex_lock(&mgr->lock);
+	if (mgr->mst_primary)
+		rmstb = drm_dp_mst_get_validated_mstb_ref_locked(mgr->mst_primary, mstb);
+	mutex_unlock(&mgr->lock);
+	return rmstb;
+}
+
+static struct drm_dp_mst_port *drm_dp_mst_get_port_ref_locked(struct drm_dp_mst_branch *mstb, struct drm_dp_mst_port *to_find)
+{
+	struct drm_dp_mst_port *port, *mport;
+
+	list_for_each_entry(port, &mstb->ports, next) {
+		if (port == to_find) {
+			kref_get(&port->kref);
+			return port;
+		}
+		if (port->mstb) {
+			mport = drm_dp_mst_get_port_ref_locked(port->mstb, to_find);
+			if (mport)
+				return mport;
+		}
+	}
+	return NULL;
+}
+
+static struct drm_dp_mst_port *drm_dp_get_validated_port_ref(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
+{
+	struct drm_dp_mst_port *rport = NULL;
+	mutex_lock(&mgr->lock);
+	if (mgr->mst_primary)
+		rport = drm_dp_mst_get_port_ref_locked(mgr->mst_primary, port);
+	mutex_unlock(&mgr->lock);
+	return rport;
+}
+
+static struct drm_dp_mst_port *drm_dp_get_port(struct drm_dp_mst_branch *mstb, u8 port_num)
+{
+	struct drm_dp_mst_port *port;
+
+	list_for_each_entry(port, &mstb->ports, next) {
+		if (port->port_num == port_num) {
+			kref_get(&port->kref);
+			return port;
+		}
+	}
+
+	return NULL;
+}
+
+/*
+ * calculate a new RAD for this MST branch device
+ * if parent has an LCT of 2 then it has 1 nibble of RAD,
+ * if parent has an LCT of 3 then it has 2 nibbles of RAD,
+ */
+static u8 drm_dp_calculate_rad(struct drm_dp_mst_port *port,
+				 u8 *rad)
+{
+	int lct = port->parent->lct;
+	int shift = 4;
+	int idx = lct / 2;
+	if (lct > 1) {
+		memcpy(rad, port->parent->rad, idx);
+		shift = (lct % 2) ? 4 : 0;
+	} else
+		rad[0] = 0;
+
+	rad[idx] |= port->port_num << shift;
+	return lct + 1;
+}
+
+/*
+ * return sends link address for new mstb
+ */
+static bool drm_dp_port_setup_pdt(struct drm_dp_mst_port *port)
+{
+	int ret;
+	u8 rad[6], lct;
+	bool send_link = false;
+	switch (port->pdt) {
+	case DP_PEER_DEVICE_DP_LEGACY_CONV:
+	case DP_PEER_DEVICE_SST_SINK:
+		/* add i2c over sideband */
+		ret = drm_dp_mst_register_i2c_bus(&port->aux);
+		break;
+	case DP_PEER_DEVICE_MST_BRANCHING:
+		lct = drm_dp_calculate_rad(port, rad);
+
+		port->mstb = drm_dp_add_mst_branch_device(lct, rad);
+		port->mstb->mgr = port->mgr;
+		port->mstb->port_parent = port;
+
+		send_link = true;
+		break;
+	}
+	return send_link;
+}
+
+static void drm_dp_check_port_guid(struct drm_dp_mst_branch *mstb,
+				   struct drm_dp_mst_port *port)
+{
+	int ret;
+	if (port->dpcd_rev >= 0x12) {
+		port->guid_valid = drm_dp_validate_guid(mstb->mgr, port->guid);
+		if (!port->guid_valid) {
+			ret = drm_dp_send_dpcd_write(mstb->mgr,
+						     port,
+						     DP_GUID,
+						     16, port->guid);
+			port->guid_valid = true;
+		}
+	}
+}
+
+static void build_mst_prop_path(struct drm_dp_mst_port *port,
+				struct drm_dp_mst_branch *mstb,
+				char *proppath)
+{
+	int i;
+	char temp[8];
+	snprintf(proppath, 255, "mst:%d", mstb->mgr->conn_base_id);
+	for (i = 0; i < (mstb->lct - 1); i++) {
+		int shift = (i % 2) ? 0 : 4;
+		int port_num = mstb->rad[i / 2] >> shift;
+		snprintf(temp, 8, "-%d", port_num);
+		strncat(proppath, temp, 255);
+	}
+	snprintf(temp, 8, "-%d", port->port_num);
+	strncat(proppath, temp, 255);
+}
+
+static void drm_dp_add_port(struct drm_dp_mst_branch *mstb,
+			    struct device *dev,
+			    struct drm_dp_link_addr_reply_port *port_msg)
+{
+	struct drm_dp_mst_port *port;
+	bool ret;
+	bool created = false;
+	int old_pdt = 0;
+	int old_ddps = 0;
+	port = drm_dp_get_port(mstb, port_msg->port_number);
+	if (!port) {
+		port = kzalloc(sizeof(*port), GFP_KERNEL);
+		if (!port)
+			return;
+		kref_init(&port->kref);
+		port->parent = mstb;
+		port->port_num = port_msg->port_number;
+		port->mgr = mstb->mgr;
+		port->aux.name = "DPMST";
+		port->aux.dev = dev;
+		created = true;
+	} else {
+		old_pdt = port->pdt;
+		old_ddps = port->ddps;
+	}
+
+	port->pdt = port_msg->peer_device_type;
+	port->input = port_msg->input_port;
+	port->mcs = port_msg->mcs;
+	port->ddps = port_msg->ddps;
+	port->ldps = port_msg->legacy_device_plug_status;
+	port->dpcd_rev = port_msg->dpcd_revision;
+	port->num_sdp_streams = port_msg->num_sdp_streams;
+	port->num_sdp_stream_sinks = port_msg->num_sdp_stream_sinks;
+	memcpy(port->guid, port_msg->peer_guid, 16);
+
+	/* manage mstb port lists with mgr lock - take a reference
+	   for this list */
+	if (created) {
+		mutex_lock(&mstb->mgr->lock);
+		kref_get(&port->kref);
+		list_add(&port->next, &mstb->ports);
+		mutex_unlock(&mstb->mgr->lock);
+	}
+
+	if (old_ddps != port->ddps) {
+		if (port->ddps) {
+			drm_dp_check_port_guid(mstb, port);
+			if (!port->input)
+				drm_dp_send_enum_path_resources(mstb->mgr, mstb, port);
+		} else {
+			port->guid_valid = false;
+			port->available_pbn = 0;
+			}
+	}
+
+	if (old_pdt != port->pdt && !port->input) {
+		drm_dp_port_teardown_pdt(port, old_pdt);
+
+		ret = drm_dp_port_setup_pdt(port);
+		if (ret == true) {
+			drm_dp_send_link_address(mstb->mgr, port->mstb);
+			port->mstb->link_address_sent = true;
+		}
+	}
+
+	if (created && !port->input) {
+		char proppath[255];
+		build_mst_prop_path(port, mstb, proppath);
+		port->connector = (*mstb->mgr->cbs->add_connector)(mstb->mgr, port, proppath);
+	}
+
+	/* put reference to this port */
+	drm_dp_put_port(port);
+}
+
+static void drm_dp_update_port(struct drm_dp_mst_branch *mstb,
+			       struct drm_dp_connection_status_notify *conn_stat)
+{
+	struct drm_dp_mst_port *port;
+	int old_pdt;
+	int old_ddps;
+	bool dowork = false;
+	port = drm_dp_get_port(mstb, conn_stat->port_number);
+	if (!port)
+		return;
+
+	old_ddps = port->ddps;
+	old_pdt = port->pdt;
+	port->pdt = conn_stat->peer_device_type;
+	port->mcs = conn_stat->message_capability_status;
+	port->ldps = conn_stat->legacy_device_plug_status;
+	port->ddps = conn_stat->displayport_device_plug_status;
+
+	if (old_ddps != port->ddps) {
+		if (port->ddps) {
+			drm_dp_check_port_guid(mstb, port);
+			dowork = true;
+		} else {
+			port->guid_valid = false;
+			port->available_pbn = 0;
+		}
+	}
+	if (old_pdt != port->pdt && !port->input) {
+		drm_dp_port_teardown_pdt(port, old_pdt);
+
+		if (drm_dp_port_setup_pdt(port))
+			dowork = true;
+	}
+
+	drm_dp_put_port(port);
+	if (dowork)
+		queue_work(system_long_wq, &mstb->mgr->work);
+
+}
+
+static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_topology_mgr *mgr,
+							       u8 lct, u8 *rad)
+{
+	struct drm_dp_mst_branch *mstb;
+	struct drm_dp_mst_port *port;
+	int i;
+	/* find the port by iterating down */
+	mstb = mgr->mst_primary;
+
+	for (i = 0; i < lct - 1; i++) {
+		int shift = (i % 2) ? 0 : 4;
+		int port_num = rad[i / 2] >> shift;
+
+		list_for_each_entry(port, &mstb->ports, next) {
+			if (port->port_num == port_num) {
+				if (!port->mstb) {
+					DRM_ERROR("failed to lookup MSTB with lct %d, rad %02x\n", lct, rad[0]);
+					return NULL;
+				}
+
+				mstb = port->mstb;
+				break;
+			}
+		}
+	}
+	kref_get(&mstb->kref);
+	return mstb;
+}
+
+static void drm_dp_check_and_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
+					       struct drm_dp_mst_branch *mstb)
+{
+	struct drm_dp_mst_port *port;
+
+	if (!mstb->link_address_sent) {
+		drm_dp_send_link_address(mgr, mstb);
+		mstb->link_address_sent = true;
+	}
+	list_for_each_entry(port, &mstb->ports, next) {
+		if (port->input)
+			continue;
+
+		if (!port->ddps)
+			continue;
+
+		if (!port->available_pbn)
+			drm_dp_send_enum_path_resources(mgr, mstb, port);
+
+		if (port->mstb)
+			drm_dp_check_and_send_link_address(mgr, port->mstb);
+	}
+}
+
+static void drm_dp_mst_link_probe_work(struct work_struct *work)
+{
+	struct drm_dp_mst_topology_mgr *mgr = container_of(work, struct drm_dp_mst_topology_mgr, work);
+
+	drm_dp_check_and_send_link_address(mgr, mgr->mst_primary);
+
+}
+
+static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
+				 u8 *guid)
+{
+	static u8 zero_guid[16];
+
+	if (!memcmp(guid, zero_guid, 16)) {
+		u64 salt = get_jiffies_64();
+		memcpy(&guid[0], &salt, sizeof(u64));
+		memcpy(&guid[8], &salt, sizeof(u64));
+		return false;
+	}
+	return true;
+}
+
+#if 0
+static int build_dpcd_read(struct drm_dp_sideband_msg_tx *msg, u8 port_num, u32 offset, u8 num_bytes)
+{
+	struct drm_dp_sideband_msg_req_body req;
+
+	req.req_type = DP_REMOTE_DPCD_READ;
+	req.u.dpcd_read.port_number = port_num;
+	req.u.dpcd_read.dpcd_address = offset;
+	req.u.dpcd_read.num_bytes = num_bytes;
+	drm_dp_encode_sideband_req(&req, msg);
+
+	return 0;
+}
+#endif
+
+static int drm_dp_send_sideband_msg(struct drm_dp_mst_topology_mgr *mgr,
+				    bool up, u8 *msg, int len)
+{
+	int ret;
+	int regbase = up ? DP_SIDEBAND_MSG_UP_REP_BASE : DP_SIDEBAND_MSG_DOWN_REQ_BASE;
+	int tosend, total, offset;
+	int retries = 0;
+
+retry:
+	total = len;
+	offset = 0;
+	do {
+		tosend = min3(mgr->max_dpcd_transaction_bytes, 16, total);
+
+		ret = drm_dp_dpcd_write(mgr->aux, regbase + offset,
+					&msg[offset],
+					tosend);
+		if (ret != tosend) {
+			if (ret == -EIO && retries < 5) {
+				retries++;
+				goto retry;
+			}
+			DRM_DEBUG_KMS("failed to dpcd write %d %d\n", tosend, ret);
+			WARN(1, "fail\n");
+
+			return -EIO;
+		}
+		offset += tosend;
+		total -= tosend;
+	} while (total > 0);
+	return 0;
+}
+
+static int set_hdr_from_dst_qlock(struct drm_dp_sideband_msg_hdr *hdr,
+				  struct drm_dp_sideband_msg_tx *txmsg)
+{
+	struct drm_dp_mst_branch *mstb = txmsg->dst;
+
+	/* both msg slots are full */
+	if (txmsg->seqno == -1) {
+		if (mstb->tx_slots[0] && mstb->tx_slots[1]) {
+			DRM_DEBUG_KMS("%s: failed to find slot\n", __func__);
+			return -EAGAIN;
+		}
+		if (mstb->tx_slots[0] == NULL && mstb->tx_slots[1] == NULL) {
+			txmsg->seqno = mstb->last_seqno;
+			mstb->last_seqno ^= 1;
+		} else if (mstb->tx_slots[0] == NULL)
+			txmsg->seqno = 0;
+		else
+			txmsg->seqno = 1;
+		mstb->tx_slots[txmsg->seqno] = txmsg;
+	}
+	hdr->broadcast = 0;
+	hdr->path_msg = txmsg->path_msg;
+	hdr->lct = mstb->lct;
+	hdr->lcr = mstb->lct - 1;
+	if (mstb->lct > 1)
+		memcpy(hdr->rad, mstb->rad, mstb->lct / 2);
+	hdr->seqno = txmsg->seqno;
+	return 0;
+}
+/*
+ * process a single block of the next message in the sideband queue
+ */
+static int process_single_tx_qlock(struct drm_dp_mst_topology_mgr *mgr,
+				   struct drm_dp_sideband_msg_tx *txmsg,
+				   bool up)
+{
+	u8 chunk[48];
+	struct drm_dp_sideband_msg_hdr hdr;
+	int len, space, idx, tosend;
+	int ret;
+
+	if (txmsg->state == DRM_DP_SIDEBAND_TX_QUEUED) {
+		txmsg->seqno = -1;
+		txmsg->state = DRM_DP_SIDEBAND_TX_START_SEND;
+	}
+
+	/* make hdr from dst mst - for replies use seqno
+	   otherwise assign one */
+	ret = set_hdr_from_dst_qlock(&hdr, txmsg);
+	if (ret < 0)
+		return ret;
+
+	/* amount left to send in this message */
+	len = txmsg->cur_len - txmsg->cur_offset;
+
+	/* 48 - sideband msg size - 1 byte for data CRC, x header bytes */
+	space = 48 - 1 - drm_dp_calc_sb_hdr_size(&hdr);
+
+	tosend = min(len, space);
+	if (len == txmsg->cur_len)
+		hdr.somt = 1;
+	if (space >= len)
+		hdr.eomt = 1;
+
+
+	hdr.msg_len = tosend + 1;
+	drm_dp_encode_sideband_msg_hdr(&hdr, chunk, &idx);
+	memcpy(&chunk[idx], &txmsg->msg[txmsg->cur_offset], tosend);
+	/* add crc at end */
+	drm_dp_crc_sideband_chunk_req(&chunk[idx], tosend);
+	idx += tosend + 1;
+
+	ret = drm_dp_send_sideband_msg(mgr, up, chunk, idx);
+	if (ret) {
+		DRM_DEBUG_KMS("sideband msg failed to send\n");
+		return ret;
+	}
+
+	txmsg->cur_offset += tosend;
+	if (txmsg->cur_offset == txmsg->cur_len) {
+		txmsg->state = DRM_DP_SIDEBAND_TX_SENT;
+		return 1;
+	}
+	return 0;
+}
+
+/* must be called holding qlock */
+static void process_single_down_tx_qlock(struct drm_dp_mst_topology_mgr *mgr)
+{
+	struct drm_dp_sideband_msg_tx *txmsg;
+	int ret;
+
+	/* construct a chunk from the first msg in the tx_msg queue */
+	if (list_empty(&mgr->tx_msg_downq)) {
+		mgr->tx_down_in_progress = false;
+		return;
+	}
+	mgr->tx_down_in_progress = true;
+
+	txmsg = list_first_entry(&mgr->tx_msg_downq, struct drm_dp_sideband_msg_tx, next);
+	ret = process_single_tx_qlock(mgr, txmsg, false);
+	if (ret == 1) {
+		/* txmsg is sent it should be in the slots now */
+		list_del(&txmsg->next);
+	} else if (ret) {
+		DRM_DEBUG_KMS("failed to send msg in q %d\n", ret);
+		list_del(&txmsg->next);
+		if (txmsg->seqno != -1)
+			txmsg->dst->tx_slots[txmsg->seqno] = NULL;
+		txmsg->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
+		wake_up(&mgr->tx_waitq);
+	}
+	if (list_empty(&mgr->tx_msg_downq)) {
+		mgr->tx_down_in_progress = false;
+		return;
+	}
+}
+
+/* called holding qlock */
+static void process_single_up_tx_qlock(struct drm_dp_mst_topology_mgr *mgr)
+{
+	struct drm_dp_sideband_msg_tx *txmsg;
+	int ret;
+
+	/* construct a chunk from the first msg in the tx_msg queue */
+	if (list_empty(&mgr->tx_msg_upq)) {
+		mgr->tx_up_in_progress = false;
+		return;
+	}
+
+	txmsg = list_first_entry(&mgr->tx_msg_upq, struct drm_dp_sideband_msg_tx, next);
+	ret = process_single_tx_qlock(mgr, txmsg, true);
+	if (ret == 1) {
+		/* up txmsgs aren't put in slots - so free after we send it */
+		list_del(&txmsg->next);
+		kfree(txmsg);
+	} else if (ret)
+		DRM_DEBUG_KMS("failed to send msg in q %d\n", ret);
+	mgr->tx_up_in_progress = true;
+}
+
+static void drm_dp_queue_down_tx(struct drm_dp_mst_topology_mgr *mgr,
+				 struct drm_dp_sideband_msg_tx *txmsg)
+{
+	mutex_lock(&mgr->qlock);
+	list_add_tail(&txmsg->next, &mgr->tx_msg_downq);
+	if (!mgr->tx_down_in_progress)
+		process_single_down_tx_qlock(mgr);
+	mutex_unlock(&mgr->qlock);
+}
+
+static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
+				    struct drm_dp_mst_branch *mstb)
+{
+	int len;
+	struct drm_dp_sideband_msg_tx *txmsg;
+	int ret;
+
+	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
+	if (!txmsg)
+		return -ENOMEM;
+
+	txmsg->dst = mstb;
+	len = build_link_address(txmsg);
+
+	drm_dp_queue_down_tx(mgr, txmsg);
+
+	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
+	if (ret > 0) {
+		int i;
+
+		if (txmsg->reply.reply_type == 1)
+			DRM_DEBUG_KMS("link address nak received\n");
+		else {
+			DRM_DEBUG_KMS("link address reply: %d\n", txmsg->reply.u.link_addr.nports);
+			for (i = 0; i < txmsg->reply.u.link_addr.nports; i++) {
+				DRM_DEBUG_KMS("port %d: input %d, pdt: %d, pn: %d, dpcd_rev: %02x, mcs: %d, ddps: %d, ldps %d, sdp %d/%d\n", i,
+				       txmsg->reply.u.link_addr.ports[i].input_port,
+				       txmsg->reply.u.link_addr.ports[i].peer_device_type,
+				       txmsg->reply.u.link_addr.ports[i].port_number,
+				       txmsg->reply.u.link_addr.ports[i].dpcd_revision,
+				       txmsg->reply.u.link_addr.ports[i].mcs,
+				       txmsg->reply.u.link_addr.ports[i].ddps,
+				       txmsg->reply.u.link_addr.ports[i].legacy_device_plug_status,
+				       txmsg->reply.u.link_addr.ports[i].num_sdp_streams,
+				       txmsg->reply.u.link_addr.ports[i].num_sdp_stream_sinks);
+			}
+			for (i = 0; i < txmsg->reply.u.link_addr.nports; i++) {
+				drm_dp_add_port(mstb, mgr->dev, &txmsg->reply.u.link_addr.ports[i]);
+			}
+			(*mgr->cbs->hotplug)(mgr);
+		}
+	} else
+		DRM_DEBUG_KMS("link address failed %d\n", ret);
+
+	kfree(txmsg);
+	return 0;
+}
+
+static int drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
+					   struct drm_dp_mst_branch *mstb,
+					   struct drm_dp_mst_port *port)
+{
+	int len;
+	struct drm_dp_sideband_msg_tx *txmsg;
+	int ret;
+
+	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
+	if (!txmsg)
+		return -ENOMEM;
+
+	txmsg->dst = mstb;
+	len = build_enum_path_resources(txmsg, port->port_num);
+
+	drm_dp_queue_down_tx(mgr, txmsg);
+
+	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
+	if (ret > 0) {
+		if (txmsg->reply.reply_type == 1)
+			DRM_DEBUG_KMS("enum path resources nak received\n");
+		else {
+			if (port->port_num != txmsg->reply.u.path_resources.port_number)
+				DRM_ERROR("got incorrect port in response\n");
+			DRM_DEBUG_KMS("enum path resources %d: %d %d\n", txmsg->reply.u.path_resources.port_number, txmsg->reply.u.path_resources.full_payload_bw_number,
+			       txmsg->reply.u.path_resources.avail_payload_bw_number);
+			port->available_pbn = txmsg->reply.u.path_resources.avail_payload_bw_number;
+		}
+	}
+
+	kfree(txmsg);
+	return 0;
+}
+
+int drm_dp_payload_send_msg(struct drm_dp_mst_topology_mgr *mgr,
+			    struct drm_dp_mst_port *port,
+			    int id,
+			    int pbn)
+{
+	struct drm_dp_sideband_msg_tx *txmsg;
+	struct drm_dp_mst_branch *mstb;
+	int len, ret;
+
+	mstb = drm_dp_get_validated_mstb_ref(mgr, port->parent);
+	if (!mstb)
+		return -EINVAL;
+
+	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
+	if (!txmsg) {
+		ret = -ENOMEM;
+		goto fail_put;
+	}
+
+	txmsg->dst = mstb;
+	len = build_allocate_payload(txmsg, port->port_num,
+				     id,
+				     pbn);
+
+	drm_dp_queue_down_tx(mgr, txmsg);
+
+	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
+	if (ret > 0) {
+		if (txmsg->reply.reply_type == 1) {
+			ret = -EINVAL;
+		} else
+			ret = 0;
+	}
+	kfree(txmsg);
+fail_put:
+	drm_dp_put_mst_branch_device(mstb);
+	return ret;
+}
+
+static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
+				       int id,
+				       struct drm_dp_payload *payload)
+{
+	int ret;
+
+	ret = drm_dp_dpcd_write_payload(mgr, id, payload);
+	if (ret < 0) {
+		payload->payload_state = 0;
+		return ret;
+	}
+	payload->payload_state = DP_PAYLOAD_LOCAL;
+	return 0;
+}
+
+int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
+				struct drm_dp_mst_port *port,
+				int id,
+				struct drm_dp_payload *payload)
+{
+	int ret;
+	ret = drm_dp_payload_send_msg(mgr, port, id, port->vcpi.pbn);
+	if (ret < 0)
+		return ret;
+	payload->payload_state = DP_PAYLOAD_REMOTE;
+	return ret;
+}
+
+int drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
+				 struct drm_dp_mst_port *port,
+				 int id,
+				 struct drm_dp_payload *payload)
+{
+	DRM_DEBUG_KMS("\n");
+	/* its okay for these to fail */
+	if (port) {
+		drm_dp_payload_send_msg(mgr, port, id, 0);
+	}
+
+	drm_dp_dpcd_write_payload(mgr, id, payload);
+	payload->payload_state = 0;
+	return 0;
+}
+
+int drm_dp_destroy_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
+				 int id,
+				 struct drm_dp_payload *payload)
+{
+	payload->payload_state = 0;
+	return 0;
+}
+
+/**
+ * drm_dp_update_payload_part1() - Execute payload update part 1
+ * @mgr: manager to use.
+ *
+ * This iterates over all proposed virtual channels, and tries to
+ * allocate space in the link for them. For 0->slots transitions,
+ * this step just writes the VCPI to the MST device. For slots->0
+ * transitions, this writes the updated VCPIs and removes the
+ * remote VC payloads.
+ *
+ * after calling this the driver should generate ACT and payload
+ * packets.
+ */
+int drm_dp_update_payload_part1(struct drm_dp_mst_topology_mgr *mgr)
+{
+	int i;
+	int cur_slots = 1;
+	struct drm_dp_payload req_payload;
+	struct drm_dp_mst_port *port;
+
+	mutex_lock(&mgr->payload_lock);
+	for (i = 0; i < mgr->max_payloads; i++) {
+		/* solve the current payloads - compare to the hw ones
+		   - update the hw view */
+		req_payload.start_slot = cur_slots;
+		if (mgr->proposed_vcpis[i]) {
+			port = container_of(mgr->proposed_vcpis[i], struct drm_dp_mst_port, vcpi);
+			req_payload.num_slots = mgr->proposed_vcpis[i]->num_slots;
+		} else {
+			port = NULL;
+			req_payload.num_slots = 0;
+		}
+		/* work out what is required to happen with this payload */
+		if (mgr->payloads[i].start_slot != req_payload.start_slot ||
+		    mgr->payloads[i].num_slots != req_payload.num_slots) {
+
+			/* need to push an update for this payload */
+			if (req_payload.num_slots) {
+				drm_dp_create_payload_step1(mgr, i + 1, &req_payload);
+				mgr->payloads[i].num_slots = req_payload.num_slots;
+			} else if (mgr->payloads[i].num_slots) {
+				mgr->payloads[i].num_slots = 0;
+				drm_dp_destroy_payload_step1(mgr, port, i + 1, &mgr->payloads[i]);
+				req_payload.payload_state = mgr->payloads[i].payload_state;
+			} else
+				req_payload.payload_state = 0;
+
+			mgr->payloads[i].start_slot = req_payload.start_slot;
+			mgr->payloads[i].payload_state = req_payload.payload_state;
+		}
+		cur_slots += req_payload.num_slots;
+	}
+	mutex_unlock(&mgr->payload_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_update_payload_part1);
+
+/**
+ * drm_dp_update_payload_part2() - Execute payload update part 2
+ * @mgr: manager to use.
+ *
+ * This iterates over all proposed virtual channels, and tries to
+ * allocate space in the link for them. For 0->slots transitions,
+ * this step writes the remote VC payload commands. For slots->0
+ * this just resets some internal state.
+ */
+int drm_dp_update_payload_part2(struct drm_dp_mst_topology_mgr *mgr)
+{
+	struct drm_dp_mst_port *port;
+	int i;
+	int ret;
+	mutex_lock(&mgr->payload_lock);
+	for (i = 0; i < mgr->max_payloads; i++) {
+
+		if (!mgr->proposed_vcpis[i])
+			continue;
+
+		port = container_of(mgr->proposed_vcpis[i], struct drm_dp_mst_port, vcpi);
+
+		DRM_DEBUG_KMS("payload %d %d\n", i, mgr->payloads[i].payload_state);
+		if (mgr->payloads[i].payload_state == DP_PAYLOAD_LOCAL) {
+			ret = drm_dp_create_payload_step2(mgr, port, i + 1, &mgr->payloads[i]);
+		} else if (mgr->payloads[i].payload_state == DP_PAYLOAD_DELETE_LOCAL) {
+			ret = drm_dp_destroy_payload_step2(mgr, i + 1, &mgr->payloads[i]);
+		}
+		if (ret) {
+			mutex_unlock(&mgr->payload_lock);
+			return ret;
+		}
+	}
+	mutex_unlock(&mgr->payload_lock);
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_update_payload_part2);
+
+#if 0 /* unused as of yet */
+static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
+				 struct drm_dp_mst_port *port,
+				 int offset, int size)
+{
+	int len;
+	struct drm_dp_sideband_msg_tx *txmsg;
+
+	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
+	if (!txmsg)
+		return -ENOMEM;
+
+	len = build_dpcd_read(txmsg, port->port_num, 0, 8);
+	txmsg->dst = port->parent;
+
+	drm_dp_queue_down_tx(mgr, txmsg);
+
+	return 0;
+}
+#endif
+
+static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
+				  struct drm_dp_mst_port *port,
+				  int offset, int size, u8 *bytes)
+{
+	int len;
+	int ret;
+	struct drm_dp_sideband_msg_tx *txmsg;
+	struct drm_dp_mst_branch *mstb;
+
+	mstb = drm_dp_get_validated_mstb_ref(mgr, port->parent);
+	if (!mstb)
+		return -EINVAL;
+
+	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
+	if (!txmsg) {
+		ret = -ENOMEM;
+		goto fail_put;
+	}
+
+	len = build_dpcd_write(txmsg, port->port_num, offset, size, bytes);
+	txmsg->dst = mstb;
+
+	drm_dp_queue_down_tx(mgr, txmsg);
+
+	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
+	if (ret > 0) {
+		if (txmsg->reply.reply_type == 1) {
+			ret = -EINVAL;
+		} else
+			ret = 0;
+	}
+	kfree(txmsg);
+fail_put:
+	drm_dp_put_mst_branch_device(mstb);
+	return ret;
+}
+
+static int drm_dp_encode_up_ack_reply(struct drm_dp_sideband_msg_tx *msg, u8 req_type)
+{
+	struct drm_dp_sideband_msg_reply_body reply;
+
+	reply.reply_type = 1;
+	reply.req_type = req_type;
+	drm_dp_encode_sideband_reply(&reply, msg);
+	return 0;
+}
+
+static int drm_dp_send_up_ack_reply(struct drm_dp_mst_topology_mgr *mgr,
+				    struct drm_dp_mst_branch *mstb,
+				    int req_type, int seqno, bool broadcast)
+{
+	struct drm_dp_sideband_msg_tx *txmsg;
+
+	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
+	if (!txmsg)
+		return -ENOMEM;
+
+	txmsg->dst = mstb;
+	txmsg->seqno = seqno;
+	drm_dp_encode_up_ack_reply(txmsg, req_type);
+
+	mutex_lock(&mgr->qlock);
+	list_add_tail(&txmsg->next, &mgr->tx_msg_upq);
+	if (!mgr->tx_up_in_progress) {
+		process_single_up_tx_qlock(mgr);
+	}
+	mutex_unlock(&mgr->qlock);
+	return 0;
+}
+
+static int drm_dp_get_vc_payload_bw(int dp_link_bw, int dp_link_count)
+{
+	switch (dp_link_bw) {
+	case DP_LINK_BW_1_62:
+		return 3 * dp_link_count;
+	case DP_LINK_BW_2_7:
+		return 5 * dp_link_count;
+	case DP_LINK_BW_5_4:
+		return 10 * dp_link_count;
+	}
+	return 0;
+}
+
+/**
+ * drm_dp_mst_topology_mgr_set_mst() - Set the MST state for a topology manager
+ * @mgr: manager to set state for
+ * @mst_state: true to enable MST on this connector - false to disable.
+ *
+ * This is called by the driver when it detects an MST capable device plugged
+ * into a DP MST capable port, or when a DP MST capable device is unplugged.
+ */
+int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state)
+{
+	int ret = 0;
+	struct drm_dp_mst_branch *mstb = NULL;
+
+	mutex_lock(&mgr->lock);
+	if (mst_state == mgr->mst_state)
+		goto out_unlock;
+
+	mgr->mst_state = mst_state;
+	/* set the device into MST mode */
+	if (mst_state) {
+		WARN_ON(mgr->mst_primary);
+
+		/* get dpcd info */
+		ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd, DP_RECEIVER_CAP_SIZE);
+		if (ret != DP_RECEIVER_CAP_SIZE) {
+			DRM_DEBUG_KMS("failed to read DPCD\n");
+			goto out_unlock;
+		}
+
+		mgr->pbn_div = drm_dp_get_vc_payload_bw(mgr->dpcd[1], mgr->dpcd[2] & DP_MAX_LANE_COUNT_MASK);
+		mgr->total_pbn = 2560;
+		mgr->total_slots = DIV_ROUND_UP(mgr->total_pbn, mgr->pbn_div);
+		mgr->avail_slots = mgr->total_slots;
+
+		/* add initial branch device at LCT 1 */
+		mstb = drm_dp_add_mst_branch_device(1, NULL);
+		if (mstb == NULL) {
+			ret = -ENOMEM;
+			goto out_unlock;
+		}
+		mstb->mgr = mgr;
+
+		/* give this the main reference */
+		mgr->mst_primary = mstb;
+		kref_get(&mgr->mst_primary->kref);
+
+		{
+			struct drm_dp_payload reset_pay;
+			reset_pay.start_slot = 0;
+			reset_pay.num_slots = 0x3f;
+			drm_dp_dpcd_write_payload(mgr, 0, &reset_pay);
+		}
+
+		ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
+					 DP_MST_EN | DP_UP_REQ_EN | DP_UPSTREAM_IS_SRC);
+		if (ret < 0) {
+			goto out_unlock;
+		}
+
+
+		/* sort out guid */
+		ret = drm_dp_dpcd_read(mgr->aux, DP_GUID, mgr->guid, 16);
+		if (ret != 16) {
+			DRM_DEBUG_KMS("failed to read DP GUID %d\n", ret);
+			goto out_unlock;
+		}
+
+		mgr->guid_valid = drm_dp_validate_guid(mgr, mgr->guid);
+		if (!mgr->guid_valid) {
+			ret = drm_dp_dpcd_write(mgr->aux, DP_GUID, mgr->guid, 16);
+			mgr->guid_valid = true;
+		}
+
+		queue_work(system_long_wq, &mgr->work);
+
+		ret = 0;
+	} else {
+		/* disable MST on the device */
+		mstb = mgr->mst_primary;
+		mgr->mst_primary = NULL;
+		/* this can fail if the device is gone */
+		drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0);
+		ret = 0;
+		memset(mgr->payloads, 0, mgr->max_payloads * sizeof(struct drm_dp_payload));
+		mgr->payload_mask = 0;
+		set_bit(0, &mgr->payload_mask);
+	}
+
+out_unlock:
+	mutex_unlock(&mgr->lock);
+	if (mstb)
+		drm_dp_put_mst_branch_device(mstb);
+	return ret;
+
+}
+EXPORT_SYMBOL(drm_dp_mst_topology_mgr_set_mst);
+
+/**
+ * drm_dp_mst_topology_mgr_suspend() - suspend the MST manager
+ * @mgr: manager to suspend
+ *
+ * This function tells the MST device that we can't handle UP messages
+ * anymore. This should stop it from sending any since we are suspended.
+ */
+void drm_dp_mst_topology_mgr_suspend(struct drm_dp_mst_topology_mgr *mgr)
+{
+	mutex_lock(&mgr->lock);
+	drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
+			   DP_MST_EN | DP_UPSTREAM_IS_SRC);
+	mutex_unlock(&mgr->lock);
+}
+EXPORT_SYMBOL(drm_dp_mst_topology_mgr_suspend);
+
+/**
+ * drm_dp_mst_topology_mgr_resume() - resume the MST manager
+ * @mgr: manager to resume
+ *
+ * This will fetch DPCD and see if the device is still there,
+ * if it is, it will rewrite the MSTM control bits, and return.
+ *
+ * if the device fails this returns -1, and the driver should do
+ * a full MST reprobe, in case we were undocked.
+ */
+int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr)
+{
+	int ret = 0;
+
+	mutex_lock(&mgr->lock);
+
+	if (mgr->mst_primary) {
+		int sret;
+		sret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd, DP_RECEIVER_CAP_SIZE);
+		if (sret != DP_RECEIVER_CAP_SIZE) {
+			DRM_DEBUG_KMS("dpcd read failed - undocked during suspend?\n");
+			ret = -1;
+			goto out_unlock;
+		}
+
+		ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
+					 DP_MST_EN | DP_UP_REQ_EN | DP_UPSTREAM_IS_SRC);
+		if (ret < 0) {
+			DRM_DEBUG_KMS("mst write failed - undocked during suspend?\n");
+			ret = -1;
+			goto out_unlock;
+		}
+		ret = 0;
+	} else
+		ret = -1;
+
+out_unlock:
+	mutex_unlock(&mgr->lock);
+	return ret;
+}
+EXPORT_SYMBOL(drm_dp_mst_topology_mgr_resume);
+
+static void drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up)
+{
+	int len;
+	u8 replyblock[32];
+	int replylen, origlen, curreply;
+	int ret;
+	struct drm_dp_sideband_msg_rx *msg;
+	int basereg = up ? DP_SIDEBAND_MSG_UP_REQ_BASE : DP_SIDEBAND_MSG_DOWN_REP_BASE;
+	msg = up ? &mgr->up_req_recv : &mgr->down_rep_recv;
+
+	len = min(mgr->max_dpcd_transaction_bytes, 16);
+	ret = drm_dp_dpcd_read(mgr->aux, basereg,
+			       replyblock, len);
+	if (ret != len) {
+		DRM_DEBUG_KMS("failed to read DPCD down rep %d %d\n", len, ret);
+		return;
+	}
+	ret = drm_dp_sideband_msg_build(msg, replyblock, len, true);
+	if (!ret) {
+		DRM_DEBUG_KMS("sideband msg build failed %d\n", replyblock[0]);
+		return;
+	}
+	replylen = msg->curchunk_len + msg->curchunk_hdrlen;
+
+	origlen = replylen;
+	replylen -= len;
+	curreply = len;
+	while (replylen > 0) {
+		len = min3(replylen, mgr->max_dpcd_transaction_bytes, 16);
+		ret = drm_dp_dpcd_read(mgr->aux, basereg + curreply,
+				    replyblock, len);
+		if (ret != len) {
+			DRM_DEBUG_KMS("failed to read a chunk\n");
+		}
+		ret = drm_dp_sideband_msg_build(msg, replyblock, len, false);
+		if (ret == false)
+			DRM_DEBUG_KMS("failed to build sideband msg\n");
+		curreply += len;
+		replylen -= len;
+	}
+}
+
+static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr)
+{
+	int ret = 0;
+
+	drm_dp_get_one_sb_msg(mgr, false);
+
+	if (mgr->down_rep_recv.have_eomt) {
+		struct drm_dp_sideband_msg_tx *txmsg;
+		struct drm_dp_mst_branch *mstb;
+		int slot = -1;
+		mstb = drm_dp_get_mst_branch_device(mgr,
+						    mgr->down_rep_recv.initial_hdr.lct,
+						    mgr->down_rep_recv.initial_hdr.rad);
+
+		if (!mstb) {
+			DRM_DEBUG_KMS("Got MST reply from unknown device %d\n", mgr->down_rep_recv.initial_hdr.lct);
+			memset(&mgr->down_rep_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
+			return 0;
+		}
+
+		/* find the message */
+		slot = mgr->down_rep_recv.initial_hdr.seqno;
+		mutex_lock(&mgr->qlock);
+		txmsg = mstb->tx_slots[slot];
+		/* remove from slots */
+		mutex_unlock(&mgr->qlock);
+
+		if (!txmsg) {
+			DRM_DEBUG_KMS("Got MST reply with no msg %p %d %d %02x %02x\n",
+			       mstb,
+			       mgr->down_rep_recv.initial_hdr.seqno,
+			       mgr->down_rep_recv.initial_hdr.lct,
+				      mgr->down_rep_recv.initial_hdr.rad[0],
+				      mgr->down_rep_recv.msg[0]);
+			drm_dp_put_mst_branch_device(mstb);
+			memset(&mgr->down_rep_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
+			return 0;
+		}
+
+		drm_dp_sideband_parse_reply(&mgr->down_rep_recv, &txmsg->reply);
+		if (txmsg->reply.reply_type == 1) {
+			DRM_DEBUG_KMS("Got NAK reply: req 0x%02x, reason 0x%02x, nak data 0x%02x\n", txmsg->reply.req_type, txmsg->reply.u.nak.reason, txmsg->reply.u.nak.nak_data);
+		}
+
+		memset(&mgr->down_rep_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
+		drm_dp_put_mst_branch_device(mstb);
+
+		mutex_lock(&mgr->qlock);
+		txmsg->state = DRM_DP_SIDEBAND_TX_RX;
+		mstb->tx_slots[slot] = NULL;
+		mutex_unlock(&mgr->qlock);
+
+		wake_up(&mgr->tx_waitq);
+	}
+	return ret;
+}
+
+static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
+{
+	int ret = 0;
+	drm_dp_get_one_sb_msg(mgr, true);
+
+	if (mgr->up_req_recv.have_eomt) {
+		struct drm_dp_sideband_msg_req_body msg;
+		struct drm_dp_mst_branch *mstb;
+		bool seqno;
+		mstb = drm_dp_get_mst_branch_device(mgr,
+						    mgr->up_req_recv.initial_hdr.lct,
+						    mgr->up_req_recv.initial_hdr.rad);
+		if (!mstb) {
+			DRM_DEBUG_KMS("Got MST reply from unknown device %d\n", mgr->up_req_recv.initial_hdr.lct);
+			memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
+			return 0;
+		}
+
+		seqno = mgr->up_req_recv.initial_hdr.seqno;
+		drm_dp_sideband_parse_req(&mgr->up_req_recv, &msg);
+
+		if (msg.req_type == DP_CONNECTION_STATUS_NOTIFY) {
+			drm_dp_send_up_ack_reply(mgr, mstb, msg.req_type, seqno, false);
+			drm_dp_update_port(mstb, &msg.u.conn_stat);
+			DRM_DEBUG_KMS("Got CSN: pn: %d ldps:%d ddps: %d mcs: %d ip: %d pdt: %d\n", msg.u.conn_stat.port_number, msg.u.conn_stat.legacy_device_plug_status, msg.u.conn_stat.displayport_device_plug_status, msg.u.conn_stat.message_capability_status, msg.u.conn_stat.input_port, msg.u.conn_stat.peer_device_type);
+			(*mgr->cbs->hotplug)(mgr);
+
+		} else if (msg.req_type == DP_RESOURCE_STATUS_NOTIFY) {
+			drm_dp_send_up_ack_reply(mgr, mstb, msg.req_type, seqno, false);
+			DRM_DEBUG_KMS("Got RSN: pn: %d avail_pbn %d\n", msg.u.resource_stat.port_number, msg.u.resource_stat.available_pbn);
+		}
+
+		drm_dp_put_mst_branch_device(mstb);
+		memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
+	}
+	return ret;
+}
+
+/**
+ * drm_dp_mst_hpd_irq() - MST hotplug IRQ notify
+ * @mgr: manager to notify irq for.
+ * @esi: 4 bytes from SINK_COUNT_ESI
+ *
+ * This should be called from the driver when it detects a short IRQ,
+ * along with the value of the DEVICE_SERVICE_IRQ_VECTOR_ESI0. The
+ * topology manager will process the sideband messages received as a result
+ * of this.
+ */
+int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled)
+{
+	int ret = 0;
+	int sc;
+	*handled = false;
+	sc = esi[0] & 0x3f;
+
+	if (sc != mgr->sink_count) {
+		mgr->sink_count = sc;
+		*handled = true;
+	}
+
+	if (esi[1] & DP_DOWN_REP_MSG_RDY) {
+		ret = drm_dp_mst_handle_down_rep(mgr);
+		*handled = true;
+	}
+
+	if (esi[1] & DP_UP_REQ_MSG_RDY) {
+		ret |= drm_dp_mst_handle_up_req(mgr);
+		*handled = true;
+	}
+
+	drm_dp_mst_kick_tx(mgr);
+	return ret;
+}
+EXPORT_SYMBOL(drm_dp_mst_hpd_irq);
+
+/**
+ * drm_dp_mst_detect_port() - get connection status for an MST port
+ * @mgr: manager for this port
+ * @port: unverified pointer to a port
+ *
+ * This returns the current connection state for a port. It validates the
+ * port pointer still exists so the caller doesn't require a reference
+ */
+enum drm_connector_status drm_dp_mst_detect_port(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
+{
+	enum drm_connector_status status = connector_status_disconnected;
+
+	/* we need to search for the port in the mgr in case its gone */
+	port = drm_dp_get_validated_port_ref(mgr, port);
+	if (!port)
+		return connector_status_disconnected;
+
+	if (!port->ddps)
+		goto out;
+
+	switch (port->pdt) {
+	case DP_PEER_DEVICE_NONE:
+	case DP_PEER_DEVICE_MST_BRANCHING:
+		break;
+
+	case DP_PEER_DEVICE_SST_SINK:
+		status = connector_status_connected;
+		break;
+	case DP_PEER_DEVICE_DP_LEGACY_CONV:
+		if (port->ldps)
+			status = connector_status_connected;
+		break;
+	}
+out:
+	drm_dp_put_port(port);
+	return status;
+}
+EXPORT_SYMBOL(drm_dp_mst_detect_port);
+
+/**
+ * drm_dp_mst_get_edid() - get EDID for an MST port
+ * @connector: toplevel connector to get EDID for
+ * @mgr: manager for this port
+ * @port: unverified pointer to a port.
+ *
+ * This returns an EDID for the port connected to a connector,
+ * It validates the pointer still exists so the caller doesn't require a
+ * reference.
+ */
+struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
+{
+	struct edid *edid = NULL;
+
+	/* we need to search for the port in the mgr in case its gone */
+	port = drm_dp_get_validated_port_ref(mgr, port);
+	if (!port)
+		return NULL;
+
+	edid = drm_get_edid(connector, &port->aux.ddc);
+	drm_dp_put_port(port);
+	return edid;
+}
+EXPORT_SYMBOL(drm_dp_mst_get_edid);
+
+/**
+ * drm_dp_find_vcpi_slots() - find slots for this PBN value
+ * @mgr: manager to use
+ * @pbn: payload bandwidth to convert into slots.
+ */
+int drm_dp_find_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr,
+			   int pbn)
+{
+	int num_slots;
+
+	num_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
+
+	if (num_slots > mgr->avail_slots)
+		return -ENOSPC;
+	return num_slots;
+}
+EXPORT_SYMBOL(drm_dp_find_vcpi_slots);
+
+static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
+			    struct drm_dp_vcpi *vcpi, int pbn)
+{
+	int num_slots;
+	int ret;
+
+	num_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
+
+	if (num_slots > mgr->avail_slots)
+		return -ENOSPC;
+
+	vcpi->pbn = pbn;
+	vcpi->aligned_pbn = num_slots * mgr->pbn_div;
+	vcpi->num_slots = num_slots;
+
+	ret = drm_dp_mst_assign_payload_id(mgr, vcpi);
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+
+/**
+ * drm_dp_mst_allocate_vcpi() - Allocate a virtual channel
+ * @mgr: manager for this port
+ * @port: port to allocate a virtual channel for.
+ * @pbn: payload bandwidth number to request
+ * @slots: returned number of slots for this PBN.
+ */
+bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port, int pbn, int *slots)
+{
+	int ret;
+
+	port = drm_dp_get_validated_port_ref(mgr, port);
+	if (!port)
+		return false;
+
+	if (port->vcpi.vcpi > 0) {
+		DRM_DEBUG_KMS("payload: vcpi %d already allocated for pbn %d - requested pbn %d\n", port->vcpi.vcpi, port->vcpi.pbn, pbn);
+		if (pbn == port->vcpi.pbn) {
+			*slots = port->vcpi.num_slots;
+			return true;
+		}
+	}
+
+	ret = drm_dp_init_vcpi(mgr, &port->vcpi, pbn);
+	if (ret) {
+		DRM_DEBUG_KMS("failed to init vcpi %d %d %d\n", DIV_ROUND_UP(pbn, mgr->pbn_div), mgr->avail_slots, ret);
+		goto out;
+	}
+	DRM_DEBUG_KMS("initing vcpi for %d %d\n", pbn, port->vcpi.num_slots);
+	*slots = port->vcpi.num_slots;
+
+	drm_dp_put_port(port);
+	return true;
+out:
+	return false;
+}
+EXPORT_SYMBOL(drm_dp_mst_allocate_vcpi);
+
+/**
+ * drm_dp_mst_reset_vcpi_slots() - Reset number of slots to 0 for VCPI
+ * @mgr: manager for this port
+ * @port: unverified pointer to a port.
+ *
+ * This just resets the number of slots for the ports VCPI for later programming.
+ */
+void drm_dp_mst_reset_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
+{
+	port = drm_dp_get_validated_port_ref(mgr, port);
+	if (!port)
+		return;
+	port->vcpi.num_slots = 0;
+	drm_dp_put_port(port);
+}
+EXPORT_SYMBOL(drm_dp_mst_reset_vcpi_slots);
+
+/**
+ * drm_dp_mst_deallocate_vcpi() - deallocate a VCPI
+ * @mgr: manager for this port
+ * @port: unverified port to deallocate vcpi for
+ */
+void drm_dp_mst_deallocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
+{
+	port = drm_dp_get_validated_port_ref(mgr, port);
+	if (!port)
+		return;
+
+	drm_dp_mst_put_payload_id(mgr, port->vcpi.vcpi);
+	port->vcpi.num_slots = 0;
+	port->vcpi.pbn = 0;
+	port->vcpi.aligned_pbn = 0;
+	port->vcpi.vcpi = 0;
+	drm_dp_put_port(port);
+}
+EXPORT_SYMBOL(drm_dp_mst_deallocate_vcpi);
+
+static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
+				     int id, struct drm_dp_payload *payload)
+{
+	u8 payload_alloc[3], status;
+	int ret;
+	int retries = 0;
+
+	drm_dp_dpcd_writeb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS,
+			   DP_PAYLOAD_TABLE_UPDATED);
+
+	payload_alloc[0] = id;
+	payload_alloc[1] = payload->start_slot;
+	payload_alloc[2] = payload->num_slots;
+
+	ret = drm_dp_dpcd_write(mgr->aux, DP_PAYLOAD_ALLOCATE_SET, payload_alloc, 3);
+	if (ret != 3) {
+		DRM_DEBUG_KMS("failed to write payload allocation %d\n", ret);
+		goto fail;
+	}
+
+retry:
+	ret = drm_dp_dpcd_readb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
+	if (ret < 0) {
+		DRM_DEBUG_KMS("failed to read payload table status %d\n", ret);
+		goto fail;
+	}
+
+	if (!(status & DP_PAYLOAD_TABLE_UPDATED)) {
+		retries++;
+		if (retries < 20) {
+			usleep_range(10000, 20000);
+			goto retry;
+		}
+		DRM_DEBUG_KMS("status not set after read payload table status %d\n", status);
+		ret = -EINVAL;
+		goto fail;
+	}
+	ret = 0;
+fail:
+	return ret;
+}
+
+
+/**
+ * drm_dp_check_act_status() - Check ACT handled status.
+ * @mgr: manager to use
+ *
+ * Check the payload status bits in the DPCD for ACT handled completion.
+ */
+int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr)
+{
+	u8 status;
+	int ret;
+	int count = 0;
+
+	do {
+		ret = drm_dp_dpcd_readb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
+
+		if (ret < 0) {
+			DRM_DEBUG_KMS("failed to read payload table status %d\n", ret);
+			goto fail;
+		}
+
+		if (status & DP_PAYLOAD_ACT_HANDLED)
+			break;
+		count++;
+		udelay(100);
+
+	} while (count < 30);
+
+	if (!(status & DP_PAYLOAD_ACT_HANDLED)) {
+		DRM_DEBUG_KMS("failed to get ACT bit %d after %d retries\n", status, count);
+		ret = -EINVAL;
+		goto fail;
+	}
+	return 0;
+fail:
+	return ret;
+}
+EXPORT_SYMBOL(drm_dp_check_act_status);
+
+/**
+ * drm_dp_calc_pbn_mode() - Calculate the PBN for a mode.
+ * @clock: dot clock for the mode
+ * @bpp: bpp for the mode.
+ *
+ * This uses the formula in the spec to calculate the PBN value for a mode.
+ */
+int drm_dp_calc_pbn_mode(int clock, int bpp)
+{
+	fixed20_12 pix_bw;
+	fixed20_12 fbpp;
+	fixed20_12 result;
+	fixed20_12 margin, tmp;
+	u32 res;
+
+	pix_bw.full = dfixed_const(clock);
+	fbpp.full = dfixed_const(bpp);
+	tmp.full = dfixed_const(8);
+	fbpp.full = dfixed_div(fbpp, tmp);
+
+	result.full = dfixed_mul(pix_bw, fbpp);
+	margin.full = dfixed_const(54);
+	tmp.full = dfixed_const(64);
+	margin.full = dfixed_div(margin, tmp);
+	result.full = dfixed_div(result, margin);
+
+	margin.full = dfixed_const(1006);
+	tmp.full = dfixed_const(1000);
+	margin.full = dfixed_div(margin, tmp);
+	result.full = dfixed_mul(result, margin);
+
+	result.full = dfixed_div(result, tmp);
+	result.full = dfixed_ceil(result);
+	res = dfixed_trunc(result);
+	return res;
+}
+EXPORT_SYMBOL(drm_dp_calc_pbn_mode);
+
+static int test_calc_pbn_mode(void)
+{
+	int ret;
+	ret = drm_dp_calc_pbn_mode(154000, 30);
+	if (ret != 689)
+		return -EINVAL;
+	ret = drm_dp_calc_pbn_mode(234000, 30);
+	if (ret != 1047)
+		return -EINVAL;
+	return 0;
+}
+
+/* we want to kick the TX after we've ack the up/down IRQs. */
+static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr)
+{
+	queue_work(system_long_wq, &mgr->tx_work);
+}
+
+static void drm_dp_mst_dump_mstb(struct seq_file *m,
+				 struct drm_dp_mst_branch *mstb)
+{
+	struct drm_dp_mst_port *port;
+	int tabs = mstb->lct;
+	char prefix[10];
+	int i;
+
+	for (i = 0; i < tabs; i++)
+		prefix[i] = '\t';
+	prefix[i] = '\0';
+
+	seq_printf(m, "%smst: %p, %d\n", prefix, mstb, mstb->num_ports);
+	list_for_each_entry(port, &mstb->ports, next) {
+		seq_printf(m, "%sport: %d: ddps: %d ldps: %d, %p, conn: %p\n", prefix, port->port_num, port->ddps, port->ldps, port, port->connector);
+		if (port->mstb)
+			drm_dp_mst_dump_mstb(m, port->mstb);
+	}
+}
+
+static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
+				  char *buf)
+{
+	int ret;
+	int i;
+	for (i = 0; i < 4; i++) {
+		ret = drm_dp_dpcd_read(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS + (i * 16), &buf[i * 16], 16);
+		if (ret != 16)
+			break;
+	}
+	if (i == 4)
+		return true;
+	return false;
+}
+
+/**
+ * drm_dp_mst_dump_topology(): dump topology to seq file.
+ * @m: seq_file to dump output to
+ * @mgr: manager to dump current topology for.
+ *
+ * helper to dump MST topology to a seq file for debugfs.
+ */
+void drm_dp_mst_dump_topology(struct seq_file *m,
+			      struct drm_dp_mst_topology_mgr *mgr)
+{
+	int i;
+	struct drm_dp_mst_port *port;
+	mutex_lock(&mgr->lock);
+	if (mgr->mst_primary)
+		drm_dp_mst_dump_mstb(m, mgr->mst_primary);
+
+	/* dump VCPIs */
+	mutex_unlock(&mgr->lock);
+
+	mutex_lock(&mgr->payload_lock);
+	seq_printf(m, "vcpi: %lx\n", mgr->payload_mask);
+
+	for (i = 0; i < mgr->max_payloads; i++) {
+		if (mgr->proposed_vcpis[i]) {
+			port = container_of(mgr->proposed_vcpis[i], struct drm_dp_mst_port, vcpi);
+			seq_printf(m, "vcpi %d: %d %d %d\n", i, port->port_num, port->vcpi.vcpi, port->vcpi.num_slots);
+		} else
+			seq_printf(m, "vcpi %d:unsed\n", i);
+	}
+	for (i = 0; i < mgr->max_payloads; i++) {
+		seq_printf(m, "payload %d: %d, %d, %d\n",
+			   i,
+			   mgr->payloads[i].payload_state,
+			   mgr->payloads[i].start_slot,
+			   mgr->payloads[i].num_slots);
+
+
+	}
+	mutex_unlock(&mgr->payload_lock);
+
+	mutex_lock(&mgr->lock);
+	if (mgr->mst_primary) {
+		u8 buf[64];
+		bool bret;
+		int ret;
+		ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, buf, DP_RECEIVER_CAP_SIZE);
+		seq_printf(m, "dpcd: ");
+		for (i = 0; i < DP_RECEIVER_CAP_SIZE; i++)
+			seq_printf(m, "%02x ", buf[i]);
+		seq_printf(m, "\n");
+		ret = drm_dp_dpcd_read(mgr->aux, DP_FAUX_CAP, buf, 2);
+		seq_printf(m, "faux/mst: ");
+		for (i = 0; i < 2; i++)
+			seq_printf(m, "%02x ", buf[i]);
+		seq_printf(m, "\n");
+		ret = drm_dp_dpcd_read(mgr->aux, DP_MSTM_CTRL, buf, 1);
+		seq_printf(m, "mst ctrl: ");
+		for (i = 0; i < 1; i++)
+			seq_printf(m, "%02x ", buf[i]);
+		seq_printf(m, "\n");
+
+		bret = dump_dp_payload_table(mgr, buf);
+		if (bret == true) {
+			seq_printf(m, "payload table: ");
+			for (i = 0; i < 63; i++)
+				seq_printf(m, "%02x ", buf[i]);
+			seq_printf(m, "\n");
+		}
+
+	}
+
+	mutex_unlock(&mgr->lock);
+
+}
+EXPORT_SYMBOL(drm_dp_mst_dump_topology);
+
+static void drm_dp_tx_work(struct work_struct *work)
+{
+	struct drm_dp_mst_topology_mgr *mgr = container_of(work, struct drm_dp_mst_topology_mgr, tx_work);
+
+	mutex_lock(&mgr->qlock);
+	if (mgr->tx_down_in_progress)
+		process_single_down_tx_qlock(mgr);
+	mutex_unlock(&mgr->qlock);
+}
+
+/**
+ * drm_dp_mst_topology_mgr_init - initialise a topology manager
+ * @mgr: manager struct to initialise
+ * @dev: device providing this structure - for i2c addition.
+ * @aux: DP helper aux channel to talk to this device
+ * @max_dpcd_transaction_bytes: hw specific DPCD transaction limit
+ * @max_payloads: maximum number of payloads this GPU can source
+ * @conn_base_id: the connector object ID the MST device is connected to.
+ *
+ * Return 0 for success, or negative error code on failure
+ */
+int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
+				 struct device *dev, struct drm_dp_aux *aux,
+				 int max_dpcd_transaction_bytes,
+				 int max_payloads, int conn_base_id)
+{
+	mutex_init(&mgr->lock);
+	mutex_init(&mgr->qlock);
+	mutex_init(&mgr->payload_lock);
+	INIT_LIST_HEAD(&mgr->tx_msg_upq);
+	INIT_LIST_HEAD(&mgr->tx_msg_downq);
+	INIT_WORK(&mgr->work, drm_dp_mst_link_probe_work);
+	INIT_WORK(&mgr->tx_work, drm_dp_tx_work);
+	init_waitqueue_head(&mgr->tx_waitq);
+	mgr->dev = dev;
+	mgr->aux = aux;
+	mgr->max_dpcd_transaction_bytes = max_dpcd_transaction_bytes;
+	mgr->max_payloads = max_payloads;
+	mgr->conn_base_id = conn_base_id;
+	mgr->payloads = kcalloc(max_payloads, sizeof(struct drm_dp_payload), GFP_KERNEL);
+	if (!mgr->payloads)
+		return -ENOMEM;
+	mgr->proposed_vcpis = kcalloc(max_payloads, sizeof(struct drm_dp_vcpi *), GFP_KERNEL);
+	if (!mgr->proposed_vcpis)
+		return -ENOMEM;
+	set_bit(0, &mgr->payload_mask);
+	test_calc_pbn_mode();
+	return 0;
+}
+EXPORT_SYMBOL(drm_dp_mst_topology_mgr_init);
+
+/**
+ * drm_dp_mst_topology_mgr_destroy() - destroy topology manager.
+ * @mgr: manager to destroy
+ */
+void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr)
+{
+	mutex_lock(&mgr->payload_lock);
+	kfree(mgr->payloads);
+	mgr->payloads = NULL;
+	kfree(mgr->proposed_vcpis);
+	mgr->proposed_vcpis = NULL;
+	mutex_unlock(&mgr->payload_lock);
+	mgr->dev = NULL;
+	mgr->aux = NULL;
+}
+EXPORT_SYMBOL(drm_dp_mst_topology_mgr_destroy);
+
+/* I2C device */
+static int drm_dp_mst_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
+			       int num)
+{
+	struct drm_dp_aux *aux = adapter->algo_data;
+	struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port, aux);
+	struct drm_dp_mst_branch *mstb;
+	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
+	unsigned int i;
+	bool reading = false;
+	struct drm_dp_sideband_msg_req_body msg;
+	struct drm_dp_sideband_msg_tx *txmsg = NULL;
+	int ret;
+
+	mstb = drm_dp_get_validated_mstb_ref(mgr, port->parent);
+	if (!mstb)
+		return -EREMOTEIO;
+
+	/* construct i2c msg */
+	/* see if last msg is a read */
+	if (msgs[num - 1].flags & I2C_M_RD)
+		reading = true;
+
+	if (!reading) {
+		DRM_DEBUG_KMS("Unsupported I2C transaction for MST device\n");
+		ret = -EIO;
+		goto out;
+	}
+
+	msg.req_type = DP_REMOTE_I2C_READ;
+	msg.u.i2c_read.num_transactions = num - 1;
+	msg.u.i2c_read.port_number = port->port_num;
+	for (i = 0; i < num - 1; i++) {
+		msg.u.i2c_read.transactions[i].i2c_dev_id = msgs[i].addr;
+		msg.u.i2c_read.transactions[i].num_bytes = msgs[i].len;
+		msg.u.i2c_read.transactions[i].bytes = msgs[i].buf;
+	}
+	msg.u.i2c_read.read_i2c_device_id = msgs[num - 1].addr;
+	msg.u.i2c_read.num_bytes_read = msgs[num - 1].len;
+
+	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
+	if (!txmsg) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	txmsg->dst = mstb;
+	drm_dp_encode_sideband_req(&msg, txmsg);
+
+	drm_dp_queue_down_tx(mgr, txmsg);
+
+	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
+	if (ret > 0) {
+
+		if (txmsg->reply.reply_type == 1) { /* got a NAK back */
+			ret = -EREMOTEIO;
+			goto out;
+		}
+		if (txmsg->reply.u.remote_i2c_read_ack.num_bytes != msgs[num - 1].len) {
+			ret = -EIO;
+			goto out;
+		}
+		memcpy(msgs[num - 1].buf, txmsg->reply.u.remote_i2c_read_ack.bytes, msgs[num - 1].len);
+		ret = num;
+	}
+out:
+	kfree(txmsg);
+	drm_dp_put_mst_branch_device(mstb);
+	return ret;
+}
+
+static u32 drm_dp_mst_i2c_functionality(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
+	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |
+	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
+	       I2C_FUNC_10BIT_ADDR;
+}
+
+static const struct i2c_algorithm drm_dp_mst_i2c_algo = {
+	.functionality = drm_dp_mst_i2c_functionality,
+	.master_xfer = drm_dp_mst_i2c_xfer,
+};
+
+/**
+ * drm_dp_mst_register_i2c_bus() - register an I2C adapter for I2C-over-AUX
+ * @aux: DisplayPort AUX channel
+ *
+ * Returns 0 on success or a negative error code on failure.
+ */
+static int drm_dp_mst_register_i2c_bus(struct drm_dp_aux *aux)
+{
+	aux->ddc.algo = &drm_dp_mst_i2c_algo;
+	aux->ddc.algo_data = aux;
+	aux->ddc.retries = 3;
+
+	aux->ddc.class = I2C_CLASS_DDC;
+	aux->ddc.owner = THIS_MODULE;
+	aux->ddc.dev.parent = aux->dev;
+	aux->ddc.dev.of_node = aux->dev->of_node;
+
+	strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev),
+		sizeof(aux->ddc.name));
+
+	return i2c_add_adapter(&aux->ddc);
+}
+
+/**
+ * drm_dp_mst_unregister_i2c_bus() - unregister an I2C-over-AUX adapter
+ * @aux: DisplayPort AUX channel
+ */
+static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_aux *aux)
+{
+	i2c_del_adapter(&aux->ddc);
+}
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
new file mode 100644
index 0000000..9b446ad
--- /dev/null
+++ b/include/drm/drm_dp_mst_helper.h
@@ -0,0 +1,509 @@
+/*
+ * Copyright © 2014 Red Hat.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission.  The copyright holders make no representations
+ * about the suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+#ifndef _DRM_DP_MST_HELPER_H_
+#define _DRM_DP_MST_HELPER_H_
+
+#include <linux/types.h>
+#include <drm/drm_dp_helper.h>
+
+struct drm_dp_mst_branch;
+
+/**
+ * struct drm_dp_vcpi - Virtual Channel Payload Identifer
+ * @vcpi: Virtual channel ID.
+ * @pbn: Payload Bandwidth Number for this channel
+ * @aligned_pbn: PBN aligned with slot size
+ * @num_slots: number of slots for this PBN
+ */
+struct drm_dp_vcpi {
+	int vcpi;
+	int pbn;
+	int aligned_pbn;
+	int num_slots;
+};
+
+/**
+ * struct drm_dp_mst_port - MST port
+ * @kref: reference count for this port.
+ * @guid_valid: for DP 1.2 devices if we have validated the GUID.
+ * @guid: guid for DP 1.2 device on this port.
+ * @port_num: port number
+ * @input: if this port is an input port.
+ * @mcs: message capability status - DP 1.2 spec.
+ * @ddps: DisplayPort Device Plug Status - DP 1.2
+ * @pdt: Peer Device Type
+ * @ldps: Legacy Device Plug Status
+ * @dpcd_rev: DPCD revision of device on this port
+ * @num_sdp_streams: Number of simultaneous streams
+ * @num_sdp_stream_sinks: Number of stream sinks
+ * @available_pbn: Available bandwidth for this port.
+ * @next: link to next port on this branch device
+ * @mstb: branch device attach below this port
+ * @aux: i2c aux transport to talk to device connected to this port.
+ * @parent: branch device parent of this port
+ * @vcpi: Virtual Channel Payload info for this port.
+ * @connector: DRM connector this port is connected to.
+ * @mgr: topology manager this port lives under.
+ *
+ * This structure represents an MST port endpoint on a device somewhere
+ * in the MST topology.
+ */
+struct drm_dp_mst_port {
+	struct kref kref;
+
+	/* if dpcd 1.2 device is on this port - its GUID info */
+	bool guid_valid;
+	u8 guid[16];
+
+	u8 port_num;
+	bool input;
+	bool mcs;
+	bool ddps;
+	u8 pdt;
+	bool ldps;
+	u8 dpcd_rev;
+	u8 num_sdp_streams;
+	u8 num_sdp_stream_sinks;
+	uint16_t available_pbn;
+	struct list_head next;
+	struct drm_dp_mst_branch *mstb; /* pointer to an mstb if this port has one */
+	struct drm_dp_aux aux; /* i2c bus for this port? */
+	struct drm_dp_mst_branch *parent;
+
+	struct drm_dp_vcpi vcpi;
+	struct drm_connector *connector;
+	struct drm_dp_mst_topology_mgr *mgr;
+};
+
+/**
+ * struct drm_dp_mst_branch - MST branch device.
+ * @kref: reference count for this port.
+ * @rad: Relative Address to talk to this branch device.
+ * @lct: Link count total to talk to this branch device.
+ * @num_ports: number of ports on the branch.
+ * @msg_slots: one bit per transmitted msg slot.
+ * @ports: linked list of ports on this branch.
+ * @port_parent: pointer to the port parent, NULL if toplevel.
+ * @mgr: topology manager for this branch device.
+ * @tx_slots: transmission slots for this device.
+ * @last_seqno: last sequence number used to talk to this.
+ * @link_address_sent: if a link address message has been sent to this device yet.
+ *
+ * This structure represents an MST branch device, there is one
+ * primary branch device at the root, along with any others connected
+ * to downstream ports
+ */
+struct drm_dp_mst_branch {
+	struct kref kref;
+	u8 rad[8];
+	u8 lct;
+	int num_ports;
+
+	int msg_slots;
+	struct list_head ports;
+
+	/* list of tx ops queue for this port */
+	struct drm_dp_mst_port *port_parent;
+	struct drm_dp_mst_topology_mgr *mgr;
+
+	/* slots are protected by mstb->mgr->qlock */
+	struct drm_dp_sideband_msg_tx *tx_slots[2];
+	int last_seqno;
+	bool link_address_sent;
+};
+
+
+/* sideband msg header - not bit struct */
+struct drm_dp_sideband_msg_hdr {
+	u8 lct;
+	u8 lcr;
+	u8 rad[8];
+	bool broadcast;
+	bool path_msg;
+	u8 msg_len;
+	bool somt;
+	bool eomt;
+	bool seqno;
+};
+
+struct drm_dp_nak_reply {
+	u8 guid[16];
+	u8 reason;
+	u8 nak_data;
+};
+
+struct drm_dp_link_address_ack_reply {
+	u8 guid[16];
+	u8 nports;
+	struct drm_dp_link_addr_reply_port {
+		bool input_port;
+		u8 peer_device_type;
+		u8 port_number;
+		bool mcs;
+		bool ddps;
+		bool legacy_device_plug_status;
+		u8 dpcd_revision;
+		u8 peer_guid[16];
+		u8 num_sdp_streams;
+		u8 num_sdp_stream_sinks;
+	} ports[16];
+};
+
+struct drm_dp_remote_dpcd_read_ack_reply {
+	u8 port_number;
+	u8 num_bytes;
+	u8 bytes[255];
+};
+
+struct drm_dp_remote_dpcd_write_ack_reply {
+	u8 port_number;
+};
+
+struct drm_dp_remote_dpcd_write_nak_reply {
+	u8 port_number;
+	u8 reason;
+	u8 bytes_written_before_failure;
+};
+
+struct drm_dp_remote_i2c_read_ack_reply {
+	u8 port_number;
+	u8 num_bytes;
+	u8 bytes[255];
+};
+
+struct drm_dp_remote_i2c_read_nak_reply {
+	u8 port_number;
+	u8 nak_reason;
+	u8 i2c_nak_transaction;
+};
+
+struct drm_dp_remote_i2c_write_ack_reply {
+	u8 port_number;
+};
+
+
+struct drm_dp_sideband_msg_rx {
+	u8 chunk[48];
+	u8 msg[256];
+	u8 curchunk_len;
+	u8 curchunk_idx; /* chunk we are parsing now */
+	u8 curchunk_hdrlen;
+	u8 curlen; /* total length of the msg */
+	bool have_somt;
+	bool have_eomt;
+	struct drm_dp_sideband_msg_hdr initial_hdr;
+};
+
+
+struct drm_dp_allocate_payload {
+	u8 port_number;
+	u8 number_sdp_streams;
+	u8 vcpi;
+	u16 pbn;
+	u8 sdp_stream_sink[8];
+};
+
+struct drm_dp_allocate_payload_ack_reply {
+	u8 port_number;
+	u8 vcpi;
+	u16 allocated_pbn;
+};
+
+struct drm_dp_connection_status_notify {
+	u8 guid[16];
+	u8 port_number;
+	bool legacy_device_plug_status;
+	bool displayport_device_plug_status;
+	bool message_capability_status;
+	bool input_port;
+	u8 peer_device_type;
+};
+
+struct drm_dp_remote_dpcd_read {
+	u8 port_number;
+	u32 dpcd_address;
+	u8 num_bytes;
+};
+
+struct drm_dp_remote_dpcd_write {
+	u8 port_number;
+	u32 dpcd_address;
+	u8 num_bytes;
+	u8 *bytes;
+};
+
+struct drm_dp_remote_i2c_read {
+	u8 num_transactions;
+	u8 port_number;
+	struct {
+		u8 i2c_dev_id;
+		u8 num_bytes;
+		u8 *bytes;
+		u8 no_stop_bit;
+		u8 i2c_transaction_delay;
+	} transactions[4];
+	u8 read_i2c_device_id;
+	u8 num_bytes_read;
+};
+
+struct drm_dp_remote_i2c_write {
+	u8 port_number;
+	u8 write_i2c_device_id;
+	u8 num_bytes;
+	u8 *bytes;
+};
+
+/* this covers ENUM_RESOURCES, POWER_DOWN_PHY, POWER_UP_PHY */
+struct drm_dp_port_number_req {
+	u8 port_number;
+};
+
+struct drm_dp_enum_path_resources_ack_reply {
+	u8 port_number;
+	u16 full_payload_bw_number;
+	u16 avail_payload_bw_number;
+};
+
+/* covers POWER_DOWN_PHY, POWER_UP_PHY */
+struct drm_dp_port_number_rep {
+	u8 port_number;
+};
+
+struct drm_dp_query_payload {
+	u8 port_number;
+	u8 vcpi;
+};
+
+struct drm_dp_resource_status_notify {
+	u8 port_number;
+	u8 guid[16];
+	u16 available_pbn;
+};
+
+struct drm_dp_query_payload_ack_reply {
+	u8 port_number;
+	u8 allocated_pbn;
+};
+
+struct drm_dp_sideband_msg_req_body {
+	u8 req_type;
+	union ack_req {
+		struct drm_dp_connection_status_notify conn_stat;
+		struct drm_dp_port_number_req port_num;
+		struct drm_dp_resource_status_notify resource_stat;
+
+		struct drm_dp_query_payload query_payload;
+		struct drm_dp_allocate_payload allocate_payload;
+
+		struct drm_dp_remote_dpcd_read dpcd_read;
+		struct drm_dp_remote_dpcd_write dpcd_write;
+
+		struct drm_dp_remote_i2c_read i2c_read;
+		struct drm_dp_remote_i2c_write i2c_write;
+	} u;
+};
+
+struct drm_dp_sideband_msg_reply_body {
+	u8 reply_type;
+	u8 req_type;
+	union ack_replies {
+		struct drm_dp_nak_reply nak;
+		struct drm_dp_link_address_ack_reply link_addr;
+		struct drm_dp_port_number_rep port_number;
+
+		struct drm_dp_enum_path_resources_ack_reply path_resources;
+		struct drm_dp_allocate_payload_ack_reply allocate_payload;
+		struct drm_dp_query_payload_ack_reply query_payload;
+
+		struct drm_dp_remote_dpcd_read_ack_reply remote_dpcd_read_ack;
+		struct drm_dp_remote_dpcd_write_ack_reply remote_dpcd_write_ack;
+		struct drm_dp_remote_dpcd_write_nak_reply remote_dpcd_write_nack;
+
+		struct drm_dp_remote_i2c_read_ack_reply remote_i2c_read_ack;
+		struct drm_dp_remote_i2c_read_nak_reply remote_i2c_read_nack;
+		struct drm_dp_remote_i2c_write_ack_reply remote_i2c_write_ack;
+	} u;
+};
+
+/* msg is queued to be put into a slot */
+#define DRM_DP_SIDEBAND_TX_QUEUED 0
+/* msg has started transmitting on a slot - still on msgq */
+#define DRM_DP_SIDEBAND_TX_START_SEND 1
+/* msg has finished transmitting on a slot - removed from msgq only in slot */
+#define DRM_DP_SIDEBAND_TX_SENT 2
+/* msg has received a response - removed from slot */
+#define DRM_DP_SIDEBAND_TX_RX 3
+#define DRM_DP_SIDEBAND_TX_TIMEOUT 4
+
+struct drm_dp_sideband_msg_tx {
+	u8 msg[256];
+	u8 chunk[48];
+	u8 cur_offset;
+	u8 cur_len;
+	struct drm_dp_mst_branch *dst;
+	struct list_head next;
+	int seqno;
+	int state;
+	bool path_msg;
+	struct drm_dp_sideband_msg_reply_body reply;
+};
+
+/* sideband msg handler */
+struct drm_dp_mst_topology_mgr;
+struct drm_dp_mst_topology_cbs {
+	/* create a connector for a port */
+	struct drm_connector *(*add_connector)(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port, char *path);
+	void (*destroy_connector)(struct drm_dp_mst_topology_mgr *mgr,
+				  struct drm_connector *connector);
+	void (*hotplug)(struct drm_dp_mst_topology_mgr *mgr);
+
+};
+
+#define DP_MAX_PAYLOAD (sizeof(unsigned long) * 8)
+
+#define DP_PAYLOAD_LOCAL 1
+#define DP_PAYLOAD_REMOTE 2
+#define DP_PAYLOAD_DELETE_LOCAL 3
+
+struct drm_dp_payload {
+	int payload_state;
+	int start_slot;
+	int num_slots;
+};
+
+/**
+ * struct drm_dp_mst_topology_mgr - DisplayPort MST manager
+ * @dev: device pointer for adding i2c devices etc.
+ * @cbs: callbacks for connector addition and destruction.
+ * @max_dpcd_transaction_bytes - maximum number of bytes to read/write in one go.
+ * @aux: aux channel for the DP connector.
+ * @max_payloads: maximum number of payloads the GPU can generate.
+ * @conn_base_id: DRM connector ID this mgr is connected to.
+ * @down_rep_recv: msg receiver state for down replies.
+ * @up_req_recv: msg receiver state for up requests.
+ * @lock: protects mst state, primary, guid, dpcd.
+ * @mst_state: if this manager is enabled for an MST capable port.
+ * @mst_primary: pointer to the primary branch device.
+ * @guid_valid: GUID valid for the primary branch device.
+ * @guid: GUID for primary port.
+ * @dpcd: cache of DPCD for primary port.
+ * @pbn_div: PBN to slots divisor.
+ *
+ * This struct represents the toplevel displayport MST topology manager.
+ * There should be one instance of this for every MST capable DP connector
+ * on the GPU.
+ */
+struct drm_dp_mst_topology_mgr {
+
+	struct device *dev;
+	struct drm_dp_mst_topology_cbs *cbs;
+	int max_dpcd_transaction_bytes;
+	struct drm_dp_aux *aux; /* auxch for this topology mgr to use */
+	int max_payloads;
+	int conn_base_id;
+
+	/* only ever accessed from the workqueue - which should be serialised */
+	struct drm_dp_sideband_msg_rx down_rep_recv;
+	struct drm_dp_sideband_msg_rx up_req_recv;
+
+	/* pointer to info about the initial MST device */
+	struct mutex lock; /* protects mst_state + primary + guid + dpcd */
+
+	bool mst_state;
+	struct drm_dp_mst_branch *mst_primary;
+	/* primary MST device GUID */
+	bool guid_valid;
+	u8 guid[16];
+	u8 dpcd[DP_RECEIVER_CAP_SIZE];
+	u8 sink_count;
+	int pbn_div;
+	int total_slots;
+	int avail_slots;
+	int total_pbn;
+
+	/* messages to be transmitted */
+	/* qlock protects the upq/downq and in_progress,
+	   the mstb tx_slots and txmsg->state once they are queued */
+	struct mutex qlock;
+	struct list_head tx_msg_downq;
+	struct list_head tx_msg_upq;
+	bool tx_down_in_progress;
+	bool tx_up_in_progress;
+
+	/* payload info + lock for it */
+	struct mutex payload_lock;
+	struct drm_dp_vcpi **proposed_vcpis;
+	struct drm_dp_payload *payloads;
+	unsigned long payload_mask;
+
+	wait_queue_head_t tx_waitq;
+	struct work_struct work;
+
+	struct work_struct tx_work;
+};
+
+int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr, struct device *dev, struct drm_dp_aux *aux, int max_dpcd_transaction_bytes, int max_payloads, int conn_base_id);
+
+void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr);
+
+
+int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state);
+
+
+int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled);
+
+
+enum drm_connector_status drm_dp_mst_detect_port(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);
+
+struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);
+
+
+int drm_dp_calc_pbn_mode(int clock, int bpp);
+
+
+bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port, int pbn, int *slots);
+
+
+void drm_dp_mst_reset_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);
+
+
+void drm_dp_mst_deallocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
+				struct drm_dp_mst_port *port);
+
+
+int drm_dp_find_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr,
+			   int pbn);
+
+
+int drm_dp_update_payload_part1(struct drm_dp_mst_topology_mgr *mgr);
+
+
+int drm_dp_update_payload_part2(struct drm_dp_mst_topology_mgr *mgr);
+
+int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr);
+
+void drm_dp_mst_dump_topology(struct seq_file *m,
+			      struct drm_dp_mst_topology_mgr *mgr);
+
+void drm_dp_mst_topology_mgr_suspend(struct drm_dp_mst_topology_mgr *mgr);
+int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr);
+#endif
