[Intel-gfx] [PATCH] drm/atomic-helper: Simplify commit tracking locking

[Daniel Vetter]

On Wed, Jun 21, 2017 at 10:30:51AM -0400, Sean Paul wrote:
> On Wed, Jun 21, 2017 at 11:16:27AM +0200, Daniel Vetter wrote:
> > The crtc->commit_lock only protects commit_list and commit_entry. If
> > we chase the pointer from the drm_atomic_state update structure, then
> > we don't need any locks (since we hold a reference already).
> > 
> > Simplify the locking accordingly.
> > 
> > Noticed while reviewing a patch from Boris.
> > 
> > Cc: Boris Brezillon <boris.brezillon at free-electrons.com>
> > Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> 
> After reading this over a few times, I've convinced myself that it does
> the right thing.
> 
> Reviewed-by: Sean Paul <seanpaul at chromium.org>

Pushed to -misc, thanks for your review.
-Daniel

> 
> 
> > ---
> >  drivers/gpu/drm/drm_atomic_helper.c | 7 +------
> >  1 file changed, 1 insertion(+), 6 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> > index 86d3093c6c9b..9bf86eb87fe1 100644
> > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > @@ -1680,9 +1680,7 @@ void drm_atomic_helper_commit_hw_done(struct drm_atomic_state *old_state)
> >  
> >  		/* backend must have consumed any event by now */
> >  		WARN_ON(new_crtc_state->event);
> > -		spin_lock(&crtc->commit_lock);
> >  		complete_all(&commit->hw_done);
> > -		spin_unlock(&crtc->commit_lock);
> >  	}
> >  }
> >  EXPORT_SYMBOL(drm_atomic_helper_commit_hw_done);
> > @@ -1711,7 +1709,6 @@ void drm_atomic_helper_commit_cleanup_done(struct drm_atomic_state *old_state)
> >  		if (WARN_ON(!commit))
> >  			continue;
> >  
> > -		spin_lock(&crtc->commit_lock);
> >  		complete_all(&commit->cleanup_done);
> >  		WARN_ON(!try_wait_for_completion(&commit->hw_done));
> >  
> > @@ -1721,8 +1718,6 @@ void drm_atomic_helper_commit_cleanup_done(struct drm_atomic_state *old_state)
> >  		if (try_wait_for_completion(&commit->flip_done))
> >  			goto del_commit;
> >  
> > -		spin_unlock(&crtc->commit_lock);
> > -
> >  		/* We must wait for the vblank event to signal our completion
> >  		 * before releasing our reference, since the vblank work does
> >  		 * not hold a reference of its own. */
> > @@ -1732,8 +1727,8 @@ void drm_atomic_helper_commit_cleanup_done(struct drm_atomic_state *old_state)
> >  			DRM_ERROR("[CRTC:%d:%s] flip_done timed out\n",
> >  				  crtc->base.id, crtc->name);
> >  
> > -		spin_lock(&crtc->commit_lock);
> >  del_commit:
> > +		spin_lock(&crtc->commit_lock);
> >  		list_del(&commit->commit_entry);
> >  		spin_unlock(&crtc->commit_lock);
> >  	}
> > -- 
> > 2.11.0
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Sean Paul, Software Engineer, Google / Chromium OS

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