Re: [PATCH] drm/i915: Introduce accurate frontbuffer tracking

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Jun 18, 2014 at 03:55:44PM +0100, Chris Wilson wrote:
> On Wed, Jun 18, 2014 at 03:01:25PM +0200, Daniel Vetter wrote:
> > +void i915_gem_update_fb_bits(struct drm_i915_gem_object *old,
> > +			     struct drm_i915_gem_object *new,
> > +			     unsigned frontbuffer_bits);
> > +
> 
> Time to be a nuisance:
> 
> i915_gem_object_track_fb()
> 
> The key part is that is operates on the object. The other is just to try
> and shorten the name as compensation.

Hm, I've thought the i915_gem part is a giveaway - I'm not too fond of the
i915_gem_obj prefix since it's so long ...

> > @@ -1062,6 +1065,7 @@ intel_disable_plane(struct drm_plane *plane)
> >  	struct drm_device *dev = plane->dev;
> >  	struct intel_plane *intel_plane = to_intel_plane(plane);
> >  	struct intel_crtc *intel_crtc;
> > +	enum pipe pipe;
> >  
> >  	if (!plane->fb)
> >  		return 0;
> > @@ -1070,6 +1074,7 @@ intel_disable_plane(struct drm_plane *plane)
> >  		return -EINVAL;
> >  
> >  	intel_crtc = to_intel_crtc(plane->crtc);
> > +	pipe = intel_crtc->pipe;
> >  
> >  	if (intel_crtc->active) {
> >  		bool primary_was_enabled = intel_crtc->primary_enabled;
> > @@ -1088,6 +1093,8 @@ intel_disable_plane(struct drm_plane *plane)
> >  
> >  		mutex_lock(&dev->struct_mutex);
> >  		intel_unpin_fb_obj(intel_plane->obj);
> > +		i915_gem_update_fb_bits(intel_plane->obj, NULL,
> > +					INTEL_FRONTBUFFER_SPRITE(pipe));
> 
> Introducing a local here for a one off, or was checkpatch in an angry
> mood with INTEL_FRONTBUFFER_SPRITE(intel_crtc->pipe) ?

Just a case of shortening the line a bit, it looks terribly ugly imo. I
hope we can prettify this once we have a bit more unified nuclear flip
logic for all planes.

> That's all I spotted, the logic looks fine. But just remind me,
> i915_gem_object_track_fb() did do a lockdep_assert_held(&dev->struct_mutex)?

Yeah, both when new or old are non-NULL, as a prep for per-object locking.
If we ever get there ;-)
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch