[Intel-gfx] [PATCH] drm/i915: Re-enable GGTT earlier during resume on pre-gen6 platforms

[David Weinehall]

On Sat, May 07, 2016 at 09:18:24PM +0300, Ville Syrjälä wrote:
> On Fri, May 06, 2016 at 09:22:49PM +0100, Chris Wilson wrote:
> > On Fri, May 06, 2016 at 09:35:55PM +0300, ville.syrjala at linux.intel.com wrote:
> > > @@ -730,9 +730,14 @@ int i915_suspend_switcheroo(struct drm_device *dev, pm_message_t state)
> > >  static int i915_drm_resume(struct drm_device *dev)
> > >  {
> > >  	struct drm_i915_private *dev_priv = dev->dev_private;
> > > +	int ret;
> > >  
> > >  	disable_rpm_wakeref_asserts(dev_priv);
> > >  
> > > +	ret = i915_ggtt_enable_hw(dev);
> > > +	if (ret)
> > > +		DRM_ERROR("failed to re-enable GGTT\n");
> > 
> > Would it not be fatal for resume as well? Failure means we can't use the
> > GGTT, so all subsequent writes will be going into a random address.
> 
> Yeah, I assume things would blow up. The question is however, what can
> we do in this case? We'd basically have to shut the entire driver down.
> I don't think we have a way to do that?

panic() seems like the answer here.  If we risk scribbling into
random memory we should make sure that we just drop everything.


Kind regards, David