Re: [PATCH] drm/atomic: Increase timeout in drm_atomic_helper_wait_for_vblanks()

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Dec 09, 2025 at 03:33:18PM +0100, Thomas Zimmermann wrote:
> Increase the timeout for vblank events from 100 ms to 1000 ms. This
> is the same fix as in commit f050da08a4ed ("drm/vblank: Increase
> timeout in drm_wait_one_vblank()") for another vblank timeout.
> 
> After merging generic DRM vblank timers [1] and converting several
> DRM drivers for virtual hardware, these drivers synchronize their
> vblank events to the display refresh rate. This can trigger timeouts
> within the DRM framework.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Link: https://lore.kernel.org/dri-devel/20250904145806.430568-1-tzimmermann@suse.de/ # [1]
> Reported-by: syzbot+fcede535e7eb57cf5b43@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/dri-devel/69381d6c.050a0220.4004e.0017.GAE@google.com/

Seems fine. This will slow things down a bit when things are
screwed up, but that slowdown is already dominated by the
massive 10 second timeouts in the atomic commit machinery,
so no big deal here.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/drm_atomic_helper.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index e641fcf8c568..e108f91bc3dd 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -1839,7 +1839,7 @@ drm_atomic_helper_wait_for_vblanks(struct drm_device *dev,
>  		ret = wait_event_timeout(*queue,
>  					 state->crtcs[i].last_vblank_count !=
>  						drm_crtc_vblank_count(crtc),
> -					 msecs_to_jiffies(100));
> +					 msecs_to_jiffies(1000));
>  
>  		WARN(!ret, "[CRTC:%d:%s] vblank wait timed out\n",
>  		     crtc->base.id, crtc->name);
> -- 
> 2.52.0

-- 
Ville Syrjälä
Intel