From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:33422 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753104AbcDMUrf (ORCPT ); Wed, 13 Apr 2016 16:47:35 -0400 Subject: Patch "drm/dp: move hw_mutex up the call stack" has been added to the 4.4-stable tree To: robdclark@gmail.com, airlied@redhat.com, daniel.vetter@ffwll.ch, dwysocha@redhat.com, gregkh@linuxfoundation.org, ville.syrjala@linux.intel.com Cc: , From: Date: Wed, 13 Apr 2016 13:47:32 -0700 Message-ID: <1460580452228157@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled drm/dp: move hw_mutex up the call stack to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-dp-move-hw_mutex-up-the-call-stack.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 7779c5e23c5132c22a219f1f5554ef81dd15ee91 Mon Sep 17 00:00:00 2001 From: Rob Clark 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 From: Rob Clark 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 Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1274157 Signed-off-by: Rob Clark Reviewed-by: Ville Syrjälä Reviewed-by: Daniel Vetter Signed-off-by: Dave Airlie Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/drm_dp_helper.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) --- a/drivers/gpu/drm/drm_dp_helper.c +++ b/drivers/gpu/drm/drm_dp_helper.c @@ -178,7 +178,7 @@ static int drm_dp_dpcd_access(struct drm { struct drm_dp_aux_msg msg; unsigned int retry; - int err; + int err = 0; memset(&msg, 0, sizeof(msg)); msg.address = offset; @@ -186,6 +186,8 @@ static int drm_dp_dpcd_access(struct drm 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 @@ -194,25 +196,24 @@ static int drm_dp_dpcd_access(struct drm */ 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(AUX_RETRY_INTERVAL, AUX_RETRY_INTERVAL + 100); @@ -221,7 +222,11 @@ static int drm_dp_dpcd_access(struct drm } DRM_DEBUG_KMS("too many retries, giving up\n"); - return -EIO; + err = -EIO; + +unlock: + mutex_unlock(&aux->hw_mutex); + return err; } /** @@ -543,9 +548,7 @@ static int drm_dp_i2c_do_msg(struct drm_ int max_retries = max(7, drm_dp_i2c_retry_count(msg, dp_aux_i2c_speed_khz)); for (retry = 0, defer_i2c = 0; retry < (max_retries + defer_i2c); retry++) { - mutex_lock(&aux->hw_mutex); ret = aux->transfer(aux, msg); - mutex_unlock(&aux->hw_mutex); if (ret < 0) { if (ret == -EBUSY) continue; @@ -684,6 +687,8 @@ static int drm_dp_i2c_xfer(struct i2c_ad memset(&msg, 0, sizeof(msg)); + mutex_lock(&aux->hw_mutex); + for (i = 0; i < num; i++) { msg.address = msgs[i].addr; drm_dp_i2c_msg_set_request(&msg, &msgs[i]); @@ -738,6 +743,8 @@ static int drm_dp_i2c_xfer(struct i2c_ad msg.size = 0; (void)drm_dp_i2c_do_msg(aux, &msg); + mutex_unlock(&aux->hw_mutex); + return err; } Patches currently in stable-queue which might be from robdclark@gmail.com are queue-4.4/drm-dp-move-hw_mutex-up-the-call-stack.patch