Re: [PATCH v2 5/8] drm/atomic: Call drm_atomic_helper_fake_vblank() from the generic commit_tail() helpers

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, Jul 02, 2018 at 09:54:32AM +0200, Daniel Vetter wrote:
> On Fri, Jun 29, 2018 at 01:17:18PM +0200, Boris Brezillon wrote:
> > Now that we have a way to fake VBLANK events when requested by the CRTC
> > hook it up to the generic commit_tail() helpers.
> > 
> > Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
> 
> I really don't like this. We've had epic amounts of bugs with atomic
> drivers failing to send out vblank events when they should, and I added a
> bunch of debug checks to make sure that doesn't happen anymore.
> 
> Now there's no way anymore for drivers to spot this until they have
> misrenderings on wayland and no idea why. Imo this should only be used by
> specific drivers, with a comment why exactly they need it.

Meh I retract, you have the special no_vblank state flag to control this.
Looks all good to me.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> -Daniel
> 
> > ---
> >  drivers/gpu/drm/drm_atomic_helper.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> > index ca586993c2a2..1a088462bc42 100644
> > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > @@ -1448,6 +1448,8 @@ void drm_atomic_helper_commit_tail(struct drm_atomic_state *old_state)
> >  
> >  	drm_atomic_helper_commit_modeset_enables(dev, old_state);
> >  
> > +	drm_atomic_helper_fake_vblank(old_state);
> > +
> >  	drm_atomic_helper_commit_hw_done(old_state);
> >  
> >  	drm_atomic_helper_wait_for_vblanks(dev, old_state);
> > @@ -1477,6 +1479,8 @@ void drm_atomic_helper_commit_tail_rpm(struct drm_atomic_state *old_state)
> >  	drm_atomic_helper_commit_planes(dev, old_state,
> >  					DRM_PLANE_COMMIT_ACTIVE_ONLY);
> >  
> > +	drm_atomic_helper_fake_vblank(old_state);
> > +
> >  	drm_atomic_helper_commit_hw_done(old_state);
> >  
> >  	drm_atomic_helper_wait_for_vblanks(dev, old_state);
> > -- 
> > 2.14.1
> > 
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

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