@@ -176,7 +176,7 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
{
struct drm_dp_aux_msg msg;
unsigned int retry;
- int err;
+ int err = 0;
memset(&msg, 0, sizeof(msg));
msg.address = offset;
@@ -184,6 +184,8 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
msg.buffer = buffer;
msg.size = size;
+ mutex_lock(&aux->hw_mutex);
+
/*
* The specification doesn't give any recommendation on how often to
* retry native transactions. We used to retry 7 times like for
@@ -192,25 +194,24 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
*/
for (retry = 0; retry < 32; retry++) {
- mutex_lock(&aux->hw_mutex);
err = aux->transfer(aux, &msg);
- mutex_unlock(&aux->hw_mutex);
if (err < 0) {
if (err == -EBUSY)
continue;
- return err;
+ goto unlock;
}
switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
case DP_AUX_NATIVE_REPLY_ACK:
if (err < size)
- return -EPROTO;
- return err;
+ err = -EPROTO;
+ goto unlock;
case DP_AUX_NATIVE_REPLY_NACK:
- return -EIO;
+ err = -EIO;
+ goto unlock;
case DP_AUX_NATIVE_REPLY_DEFER:
usleep_range(400, 500);
@@ -219,7 +220,11 @@ static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
}
DRM_DEBUG_KMS("too many retries, giving up\n");
- return -EIO;
+ err = -EIO;
+
+unlock:
+ mutex_unlock(&aux->hw_mutex);
+ return err;
}
/**
@@ -408,9 +413,7 @@ static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
* before giving up the AUX transaction.
*/
for (retry = 0; retry < 7; retry++) {
- mutex_lock(&aux->hw_mutex);
err = aux->transfer(aux, msg);
- mutex_unlock(&aux->hw_mutex);
if (err < 0) {
if (err == -EBUSY)
continue;
@@ -492,6 +495,8 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
memset(&msg, 0, sizeof(msg));
+ mutex_lock(&aux->hw_mutex);
+
for (i = 0; i < num; i++) {
msg.address = msgs[i].addr;
msg.request = (msgs[i].flags & I2C_M_RD) ?
@@ -536,6 +541,8 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
msg.size = 0;
(void)drm_dp_i2c_do_msg(aux, &msg);
+ mutex_unlock(&aux->hw_mutex);
+
return err;
}
This is a note to let you know that I have just added a patch titled drm/dp: move hw_mutex up the call stack to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.8-ckt19. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From d8d861bc0a4e3a7d43db4565f4355a9fffdf38b1 Mon Sep 17 00:00:00 2001 From: Rob Clark <robdclark@gmail.com> Date: Thu, 25 Feb 2016 16:15:05 -0500 Subject: drm/dp: move hw_mutex up the call stack MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 7779c5e23c5132c22a219f1f5554ef81dd15ee91 upstream. 1) don't let other threads trying to bang on aux channel interrupt the defer timeout/logic 2) don't let other threads interrupt the i2c over aux logic Technically, according to people who actually have the DP spec, this should not be required. In practice, it makes some troublesome Dell monitor (and perhaps others) work, so probably a case of "It's compliant if it works with windows" on the hw vendor's part.. v2: rebased to come before DPCD/AUX logging patch for easier backport to stable branches. Reported-by: Dave Wysochanski <dwysocha@redhat.com> Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1274157 Signed-off-by: Rob Clark <robdclark@gmail.com> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Dave Airlie <airlied@redhat.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/gpu/drm/drm_dp_helper.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) -- 2.7.4