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

drm/vblank: Tune drm_crtc_accurate_vblank_count() WARN down to a debug

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: drm-vblank-tune-drm_crtc_accurate_vblank_count-warn-down-to-a-debug.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 a111fbc4c44d2981f1a8fef64418685be5e30280 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= ville.syrjala@linux.intel.com Date: Mon, 23 Oct 2017 18:25:40 +0300 Subject: drm/vblank: Tune drm_crtc_accurate_vblank_count() WARN down to a debug MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

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

commit a111fbc4c44d2981f1a8fef64418685be5e30280 upstream.

Since commit 632c6e4edef1 ("drm/vblank: Fix flip event vblank count") even drivers that don't implement accurate vblank timestamps will end up using drm_crtc_accurate_vblank_count(). That leads to a WARN every time drm_crtc_arm_vblank_event() gets called. The could be as often as every frame for each active crtc.

Considering drm_crtc_accurate_vblank_count() is never any worse than the drm_vblank_count() we used previously, let's just skip the WARN unless DRM_UT_VBL is enabled. That way people won't be bothered by this unless they're debugging vblank code. And let's also change it to WARN_ONCE() so that even when you're debugging vblank code you won't get drowned by constant WARNs.

Cc: Daniel Vetter daniel@ffwll.ch Cc: "Szyprowski, Marek" m.szyprowski@samsung.com Cc: Andrzej Hajda a.hajda@samsung.com Reported-by: Andrzej Hajda a.hajda@samsung.com Fixes: 632c6e4edef1 ("drm/vblank: Fix flip event vblank count") Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20171023152540.15364-1-ville.s... Acked-by: Benjamin Gaignard benjamin.gaignard@linaro.org Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- drivers/gpu/drm/drm_vblank.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/drm_vblank.c +++ b/drivers/gpu/drm/drm_vblank.c @@ -311,8 +311,8 @@ u32 drm_crtc_accurate_vblank_count(struc u32 vblank; unsigned long flags;

- WARN(!dev->driver->get_vblank_timestamp, - "This function requires support for accurate vblank timestamps."); + WARN_ONCE(drm_debug & DRM_UT_VBL && !dev->driver->get_vblank_timestamp, + "This function requires support for accurate vblank timestamps.");

spin_lock_irqsave(&dev->vblank_time_lock, flags);

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