Re: [PATCH 2/2] drm/i915: Move drm_framebuffer_unreference out of struct_mutex for takeover

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Mar 10, 2015 at 12:32:43PM +0000, Tvrtko Ursulin wrote:
> 
> On 03/10/2015 12:19 PM, Chris Wilson wrote:
> > On Tue, Mar 10, 2015 at 12:02:28PM +0000, Tvrtko Ursulin wrote:
> >>> @@ -13707,13 +13709,18 @@ void intel_modeset_gem_init(struct drm_device *dev)
> >>>   					       NULL)) {
> >>>   			DRM_ERROR("failed to pin boot fb on pipe %d\n",
> >>>   				  to_intel_crtc(c)->pipe);
> >>> -			drm_framebuffer_unreference(c->primary->fb);
> >>> -			c->primary->fb = NULL;
> >>> -			update_state_fb(c->primary);
> >>> +			unused[n_unused++] = c->primary;
> >>>   		}
> >>>   	}
> >>>   	mutex_unlock(&dev->struct_mutex);
> >>>
> >>> +	while (n_unused--) {
> >>> +		struct drm_plane *p = unused[n_unused];
> >>> +		drm_framebuffer_unreference(p->fb);
> >>> +		p->fb = NULL;
> >>> +		update_state_fb(p);
> >>> +	}
> >>> +
> >>
> >> For this one I am not sure. Should c->primary->fb = NULL remain
> >> under the locked loop? If not what is the the mutex protecting then?
> >
> > It's a dummy mutex that only exists to keep the WARNs quiet. This phase
> > of initialisation is explicitly single-threaded.
> 
> Would it be a simpler fix then to move the mutex only around 
> pin_and_fence_fb_obj?

That would be much nicer indeed.

-- 
Ville Syrjälä
Intel OTC
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