From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= <ville.syrjala@linux.intel.com>
Subject: Re: [PATCH] drm/i915: Ignore SURFLIVE and flip counter
 when the GPU gets reset
Date: Fri, 24 Oct 2014 15:50:16 +0300
Message-ID: <20141024125016.GB4284@intel.com>
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To: Chris Wilson <chris@chris-wilson.co.uk>, intel-gfx@lists.freedesktop.org
List-Id: intel-gfx@lists.freedesktop.org

On Fri, Oct 24, 2014 at 01:40:35PM +0100, Chris Wilson wrote:
> On Wed, May 28, 2014 at 01:10:55PM +0100, Chris Wilson wrote:
> > On Tue, May 27, 2014 at 09:33:09PM +0300, ville.syrjala@linux.intel.com=
 wrote:
> > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i=
915/intel_display.c
> > > index 94ac51f..cb9dd8e 100644
> > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > @@ -8895,6 +8895,10 @@ static bool page_flip_finished(struct intel_cr=
tc *crtc)
> > >  	struct drm_device *dev =3D crtc->base.dev;
> > >  	struct drm_i915_private *dev_priv =3D dev->dev_private;
> > >  =

> > > +	if (i915_reset_in_progress(&dev_priv->gpu_error) ||
> > > +	    crtc->reset_counter !=3D atomic_read(&dev_priv->gpu_error.reset=
_counter))
> > > +		return true;
> > =

> > I really don't like this. The reset_count is incremented when the reset
> > starts, so we shouldn't get here with
> > crtc->reset_counter =3D=3D gpu_error->reset_counter && reset_in_progres=
s().
> > =

> > I'd prefer this to be
> >  if (i915_has_reset(dev_priv, crtc->reset_counter)) return true;
> > =

> > with a guard when reading the gpu reset_counter:
> > =

> >  ret =3D i915_get_reset_counter(dev_priv, &intel_crtc->reset_counter);
> >  if (ret)
> > 	goto cleanup;
> > =

> > that does something like
> > =

> >  static inline int i915_get_reset_counter(struct drm_i915_private *dev_=
priv,
> >                                           int *value)
> >  {
> >      *value =3D atomic_read(dev_priv->gpu_error.reset_counter);
> >      if (*value & I915_WEDGED)
> >      	return -EIO;
> >      if (*value & I915_RESET_IN_PROGRESS_FLAG)
> >         return -EAGAIN;
> >      return 0;
> >   }
> =

> Bleh, I've seen the light and this is overly complicated and doesn't
> actually help make the code more readable than
> =

> if (intel_crtc->reset_counter !=3D atomic_read(&dev_priv->gpu_error.reset=
_counter))
> 	return true;
> =

> The original patch is
> Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

Thanks. I think we need cc:stable on this now.

-- =

Ville Syrj=E4l=E4
Intel OTC