Patch "drm/vblank: Fix flip event vblank count" has been added to the 4.14-stable tree

Patch "drm/vblank: Fix flip event vblank count" has been added to the 4.14-stable tree

[gregkh]

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

    drm/vblank: Fix flip event vblank count

to the 4.14-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-vblank-fix-flip-event-vblank-count.patch
and it can be found in the queue-4.14 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 632c6e4edef17c40bba3be67c980d959790d142f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Tue, 10 Oct 2017 16:33:22 +0300
Subject: drm/vblank: Fix flip event vblank count
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Ville Syrjälä <ville.syrjala@linux.intel.com>

commit 632c6e4edef17c40bba3be67c980d959790d142f upstream.

On machines where the vblank interrupt fires some time after the start
of vblank (or we just manage to race with the vblank interrupt handler)
we will currently stuff a stale vblank counter value into the flip event,
and thus we'll prematurely complete the flip.

Switch over to drm_crtc_accurate_vblank_count() to make sure we have an
up to date counter value, crucially also remember to add the +1 so that
the delayed vblank interrupt won't complete the flip prematurely.

Cc: Daniel Vetter <daniel@ffwll.ch>
Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171010133322.24029-1-ville.syrjala@linux.intel.com
Reviewed-by: Daniel Vetter <daniel@ffwll.ch> #irc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/gpu/drm/drm_vblank.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/drm_vblank.c
+++ b/drivers/gpu/drm/drm_vblank.c
@@ -869,7 +869,7 @@ void drm_crtc_arm_vblank_event(struct dr
 	assert_spin_locked(&dev->event_lock);
 
 	e->pipe = pipe;
-	e->event.sequence = drm_vblank_count(dev, pipe);
+	e->event.sequence = drm_crtc_accurate_vblank_count(crtc) + 1;
 	e->event.crtc_id = crtc->base.id;
 	list_add_tail(&e->base.link, &dev->vblank_event_list);
 }


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

queue-4.14/drm-edid-don-t-send-non-zero-yq-in-avi-infoframe-for-hdmi-1.x-sinks.patch
queue-4.14/drm-vblank-fix-flip-event-vblank-count.patch
queue-4.14/drm-vblank-tune-drm_crtc_accurate_vblank_count-warn-down-to-a-debug.patch