[PATCH] drm/atomic-helper: Don't set deadline for modesets

[Daniel Vetter]

On Wed, Apr 05, 2023 at 03:25:15PM +0300, Ville Syrjälä wrote:
> On Wed, Apr 05, 2023 at 10:16:50AM +0200, Daniel Vetter wrote:
> > If the crtc is being switched on or off then the semantics of
> > computing the timestampe of the next vblank is somewhat ill-defined.
> > And indeed, the code splats with a warning in the timestamp
> > computation code. Specifically it hits the check to make sure that
> > atomic drivers have full set up the timing constants in the drm_vblank
> > structure, and that's just not the case before the crtc is actually
> > on.
> > 
> > For robustness it seems best to just not set deadlines for modesets.
> > 
> > Link: https://lore.kernel.org/dri-devel/dfc21f18-7e1e-48f0-c05a-d659b9c90b91@linaro.org/
> > Fixes: d39e48ca80c0 ("drm/atomic-helper: Set fence deadline for vblank")
> > Cc: Rob Clark <robdclark at chromium.org>
> > Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> > Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
> > Cc: Maxime Ripard <mripard at kernel.org>
> > Cc: Thomas Zimmermann <tzimmermann at suse.de>
> > Reported-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> > Tested-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org> # test patch only
> > Cc: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> > ---
> >  drivers/gpu/drm/drm_atomic_helper.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> > index f21b5a74176c..6640d80d84f3 100644
> > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > @@ -1528,6 +1528,9 @@ static void set_fence_deadline(struct drm_device *dev,
> >  	for_each_new_crtc_in_state (state, crtc, new_crtc_state, i) {
> >  		ktime_t v;
> >  
> > +		if (drm_atomic_crtc_needs_modeset(new_crtc_state))
> > +			continue;
> 
> Should this stuff also be skipped when !new_crtc_state->active?
> I didn't actually check what drm_crtc_next_vblank_start() ends
> up doing in that case.

Uh yes, I'll spin v2.
-Daniel
> 
> > +
> >  		if (drm_crtc_next_vblank_start(crtc, &v))
> >  			continue;
> >  
> > -- 
> > 2.40.0
> 
> -- 
> Ville Syrjälä
> Intel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch