[Intel-gfx] [PATCH] drm/i915: Disable FBC if BIOS reserved memory (stolen) is unavailable

[Chris Wilson]

Quoting Ville Syrjälä (2019-09-12 11:30:14)
> On Wed, Sep 11, 2019 at 06:59:26PM +0100, Chris Wilson wrote:
> > The FBC requires a couple of contiguous buffers, which we allocate from
> > stolen memory. If stolen memory is unavailable, we cannot allocate those
> > buffers and so cannot support FBC. Mark it so.
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > ---
> >  drivers/gpu/drm/i915/display/intel_fbc.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
> > index dc34b23e2320..3111ecaeabd0 100644
> > --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> > +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> > @@ -1320,6 +1320,9 @@ void intel_fbc_init(struct drm_i915_private *dev_priv)
> >       fbc->enabled = false;
> >       fbc->active = false;
> >  
> > +     if (!drm_mm_initialized(&dev_priv->mm.stolen))
> > +             mkwrite_device_info(dev_priv)->display.has_fbc = false;
> > +
> 
> Not a huge fan of this approach since it means we won't even make sure
> FBC is truly disabled. But we already do this for other reasons so I
> guess it's fine.

Fwiw, I'm experimenting with enabling stolen + iommu and so far it
hasn't died. So hopefully, this is just a temporary means to silence the
huge block of red in CI.
-Chris