Patch "drm/i915: Check DP link status on long hpd too" has been added to the 4.1-stable tree

Patch "drm/i915: Check DP link status on long hpd too" has been added to the 4.1-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    drm/i915: Check DP link status on long hpd too

to the 4.1-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-i915-check-dp-link-status-on-long-hpd-too.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From d14e7b6d1d8747826cb900db852351c550e00fdd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Thu, 20 Aug 2015 19:37:29 +0300
Subject: drm/i915: Check DP link status on long hpd too
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>

commit d14e7b6d1d8747826cb900db852351c550e00fdd upstream.

We are no longer checkling the DP link status on long hpd. We used to do
that from the .hot_plug() handler, but it was removed when MST got
introduced.

If there's no userspace we now fail to retrain the link if the sink
power is toggled (or cable yanked and replugged), meaning the user is
left staring at a blank screen. With the retraining put back that should
be fixed.

Also remove the leftover comment that referred to the old retraining
from .hot_plug().

Fixes a regression introduced in:
commit 0e32b39ceed665bfa4a77a4bc307b6652b991632
Author: Dave Airlie <airlied@redhat.com>
Date:   Fri May 2 14:02:48 2014 +1000

    drm/i915: add DP 1.2 MST support (v0.7)

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89453
Tested-by: Palmer Dabbelt <palmer@dabbelt.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=91407
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89461
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89594
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=85641
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/i915/intel_dp.c |   11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -4691,9 +4691,12 @@ intel_dp_hpd_pulse(struct intel_digital_
 
 		intel_dp_probe_oui(intel_dp);
 
-		if (!intel_dp_probe_mst(intel_dp))
+		if (!intel_dp_probe_mst(intel_dp)) {
+			drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
+			intel_dp_check_link_status(intel_dp);
+			drm_modeset_unlock(&dev->mode_config.connection_mutex);
 			goto mst_fail;
-
+		}
 	} else {
 		if (intel_dp->is_mst) {
 			if (intel_dp_check_mst_status(intel_dp) == -EINVAL)
@@ -4701,10 +4704,6 @@ intel_dp_hpd_pulse(struct intel_digital_
 		}
 
 		if (!intel_dp->is_mst) {
-			/*
-			 * we'll check the link status via the normal hot plug path later -
-			 * but for short hpds we should check it now
-			 */
 			drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
 			intel_dp_check_link_status(intel_dp);
 			drm_modeset_unlock(&dev->mode_config.connection_mutex);


Patches currently in stable-queue which might be from ville.syrjala@linux.intel.com are

queue-4.1/drm-i915-check-dp-link-status-on-long-hpd-too.patch