diff mbox series

[5/5,SRU,OEM-5.14/Jammy] drm/amd/display: Add work around for tunneled MST.

Message ID 20221006184245.891152-6-vicamo.yang@canonical.com
State New
Headers show
Series AMD Yellow Carp system hang on HDMI plug in/out over dock station | expand

Commit Message

You-Sheng Yang Oct. 6, 2022, 6:42 p.m. UTC 
From: Jimmy Kizito <Jimmy.Kizito@amd.com>

BugLink: https://bugs.launchpad.net/bugs/1991974

[Why]
Certain USB4 docks do not seem to be able to handle disabling
DSC once it has been enabled on an MST stream. This can result
in blank displays.

[How]
As a work around, always enable DSC on docks exhibiting this issue. The
flag to indicate the use of DSC for MST streams on a USB4 dock is set
during detection of the dock and only cleared when the USB4 dock is
disconnected.

Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(backported from commit c9beecc5c9626ab772160ab3f8e209abc09fa54d)
[vicamo: skip field dp_mot_reset_segment in struct dc_link]
Signed-off-by: You-Sheng Yang (vicamo) <vicamo.yang@canonical.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link.c | 16 +++++++++++++++
 .../gpu/drm/amd/display/dc/core/dc_resource.c | 20 +++++++++----------
 drivers/gpu/drm/amd/display/dc/dc.h           |  3 ++-
 drivers/gpu/drm/amd/display/dc/dc_link.h      |  2 ++
 4 files changed, 30 insertions(+), 11 deletions(-)
diff mbox series

Patch

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index c4860c2c73fd..4b523f0dd9ab 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -725,6 +725,18 @@  static bool detect_dp(struct dc_link *link,
 			dal_ddc_service_set_transaction_type(link->ddc,
 							     sink_caps->transaction_type);
 
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+			/* Apply work around for tunneled MST on certain USB4 docks. Always use DSC if dock
+			 * reports DSC support.
+			 */
+			if (link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA &&
+					link->type == dc_connection_mst_branch &&
+					link->dpcd_caps.branch_dev_id == DP_BRANCH_DEVICE_ID_90CC24 &&
+					link->dpcd_caps.dsc_caps.dsc_basic_caps.fields.dsc_support.DSC_SUPPORT &&
+					!link->dc->debug.dpia_debug.bits.disable_mst_dsc_work_around)
+				link->wa_flags.dpia_mst_dsc_always_on = true;
+#endif
+
 #if defined(CONFIG_DRM_AMD_DC_HDCP)
 			/* In case of fallback to SST when topology discovery below fails
 			 * HDCP caps will be querried again later by the upper layer (caller
@@ -1165,6 +1177,10 @@  static bool dc_link_detect_helper(struct dc_link *link,
 			LINK_INFO("link=%d, mst branch is now Disconnected\n",
 				  link->link_index);
 
+			/* Disable work around which keeps DSC on for tunneled MST on certain USB4 docks. */
+			if (link->ep_type == DISPLAY_ENDPOINT_USB4_DPIA)
+				link->wa_flags.dpia_mst_dsc_always_on = false;
+
 			dm_helpers_dp_mst_stop_top_mgr(link->ctx, link);
 
 			link->mst_stream_alloc_table.stream_count = 0;
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
index 61d028731239..7105cddf4444 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
@@ -2150,16 +2150,6 @@  enum dc_status dc_validate_global_state(
 
 	if (!new_ctx)
 		return DC_ERROR_UNEXPECTED;
-#if defined(CONFIG_DRM_AMD_DC_DCN)
-
-	/*
-	 * Update link encoder to stream assignment.
-	 * TODO: Split out reason allocation from validation.
-	 */
-	if (dc->res_pool->funcs->link_encs_assign && fast_validate == false)
-		dc->res_pool->funcs->link_encs_assign(
-			dc, new_ctx, new_ctx->streams, new_ctx->stream_count);
-#endif
 
 	if (dc->res_pool->funcs->validate_global) {
 		result = dc->res_pool->funcs->validate_global(dc, new_ctx);
@@ -2211,6 +2201,16 @@  enum dc_status dc_validate_global_state(
 		if (!dc->res_pool->funcs->validate_bandwidth(dc, new_ctx, fast_validate))
 			result = DC_FAIL_BANDWIDTH_VALIDATE;
 
+#if defined(CONFIG_DRM_AMD_DC_DCN)
+	/*
+	 * Only update link encoder to stream assignment after bandwidth validation passed.
+	 * TODO: Split out assignment and validation.
+	 */
+	if (result == DC_OK && dc->res_pool->funcs->link_encs_assign && fast_validate == false)
+		dc->res_pool->funcs->link_encs_assign(
+			dc, new_ctx, new_ctx->streams, new_ctx->stream_count);
+#endif
+
 	return result;
 }
 
diff --git a/drivers/gpu/drm/amd/display/dc/dc.h b/drivers/gpu/drm/amd/display/dc/dc.h
index c80b073ac454..957e512a4a6b 100644
--- a/drivers/gpu/drm/amd/display/dc/dc.h
+++ b/drivers/gpu/drm/amd/display/dc/dc.h
@@ -468,7 +468,8 @@  union dpia_debug_options {
 		uint32_t disable_dpia:1;
 		uint32_t force_non_lttpr:1;
 		uint32_t extend_aux_rd_interval:1;
-		uint32_t reserved:29;
+		uint32_t disable_mst_dsc_work_around:1;
+		uint32_t reserved:28;
 	} bits;
 	uint32_t raw;
 };
diff --git a/drivers/gpu/drm/amd/display/dc/dc_link.h b/drivers/gpu/drm/amd/display/dc/dc_link.h
index 9b7c32f7fd86..2fa9b4626734 100644
--- a/drivers/gpu/drm/amd/display/dc/dc_link.h
+++ b/drivers/gpu/drm/amd/display/dc/dc_link.h
@@ -175,6 +175,8 @@  struct dc_link {
 		bool dp_keep_receiver_powered;
 		bool dp_skip_DID2;
 		bool dp_skip_reset_segment;
+		/* Some USB4 docks do not handle turning off MST DSC once it has been enabled. */
+		bool dpia_mst_dsc_always_on;
 	} wa_flags;
 	struct link_mst_stream_allocation_table mst_stream_alloc_table;