Re: [PATCH] DRM: VBLANK: provide valid timestamp for EVENT_FLIP

[Eugeniy Paltsev]

On Wed, 2018-09-26 at 19:37 +0300, Ville SyrjÃlà wrote:
> On Wed, Sep 26, 2018 at 05:25:35PM +0300, Eugeniy Paltsev wrote:
> > If driver/HW doesn't support vblank functionality (for example
> > UDL driver, ARCPGU driver, ...) we always have vblank->time == 0.
> > In result we always provide zero timestamp for
> > DRM_EVENT_FLIP_COMPLETE. This breaks userspace apps (for example
> > weston) which relies on timestamp value.
> > 
> > Setup time to provide valid timestamp for DRM_EVENT_FLIP_COMPLETE
> > event.
> > 
> > Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@xxxxxxxxxxxx>
> > ---
> >  drivers/gpu/drm/drm_vblank.c | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_vblank.c b/drivers/gpu/drm/drm_vblank.c
> > index 28cdcf76b6f9..0d19aca48782 100644
> > --- a/drivers/gpu/drm/drm_vblank.c
> > +++ b/drivers/gpu/drm/drm_vblank.c
> > @@ -911,6 +911,15 @@ void drm_crtc_send_vblank_event(struct drm_crtc *crtc,
> >  
> >  	if (dev->num_crtcs > 0) {
> 
> If those drivers don't support vblank stuff why are they calling
> bldrm_vank_init() w/ num_crtcs > 0? If they didn't they'd take the
> else branch which already does what you want.

Hmm...
As I can see UDL call drm_vblank_init() with num_crtcs = 1 but UDL HW
doesn't support vblank at all.
I guess I need to fix it.

> >  		seq = drm_vblank_count_and_time(dev, pipe, &now);
> > +
> > +		/*
> > +		 * If driver/HW doesn't support vblank functionality we
> > +		 * always have vblank->time == 0. Setup time to provide valid
> > +		 * timestamp for DRM_EVENT_FLIP_COMPLETE event.
> > +		 */
> > +		if (!now && e->event.base.type == DRM_EVENT_FLIP_COMPLETE)
> > +			now = ktime_get();
> > +
> >  	} else {
> >  		seq = 0;
> >  
> > -- 
> > 2.14.4
> > 
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> 
-- 
 Eugeniy Paltsev