diff mbox series

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

Message ID 20230405081650.797972-1-daniel.vetter@ffwll.ch (mailing list archive)
State New, archived
Headers show
Series drm/atomic-helper: Don't set deadline for modesets | expand

Commit Message

Daniel Vetter April 5, 2023, 8:16 a.m. UTC
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@chromium.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Reported-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Tested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> # test patch only
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
---
 drivers/gpu/drm/drm_atomic_helper.c | 3 +++
 1 file changed, 3 insertions(+)

Comments

Ville Syrjälä April 5, 2023, 12:25 p.m. UTC | #1
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@chromium.org>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Maxime Ripard <mripard@kernel.org>
> Cc: Thomas Zimmermann <tzimmermann@suse.de>
> Reported-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Tested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> # test patch only
> Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Signed-off-by: Daniel Vetter <daniel.vetter@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.

> +
>  		if (drm_crtc_next_vblank_start(crtc, &v))
>  			continue;
>  
> -- 
> 2.40.0
Daniel Vetter April 5, 2023, 1:30 p.m. UTC | #2
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@chromium.org>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> > Cc: Maxime Ripard <mripard@kernel.org>
> > Cc: Thomas Zimmermann <tzimmermann@suse.de>
> > Reported-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > Tested-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> # test patch only
> > Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> > Signed-off-by: Daniel Vetter <daniel.vetter@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
diff mbox series

Patch

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;
+
 		if (drm_crtc_next_vblank_start(crtc, &v))
 			continue;