Re: [PATCH 6/9] drm/i915: Disable scanout VT-d workaround for TGL+

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

On Thu, Oct 24, 2024 at 10:50:06AM +0000, Hogander, Jouni wrote:
> On Wed, 2024-10-09 at 21:22 +0300, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > TGL+ should no longer need any VT-d scanout workarounds.
> > Don't apply any.
> > 
> > Not 100% sure whether pre-SNB might also suffer from this. The
> > workaround did originate on SNB but who knows if it was just
> > never caught before that. Not that I ever managed to enable
> > VT-d any older hardware. Last time I tried on my ILK it ate
> > the disk!
> 
> Any possibility to have bspec reference or is it just some offline
> documentation?

The workaround is documented in the PLANE_SURF registers.
It is there for pre-TGL and gone for TGL+.

> 
> BR,
> 
> Jouni Högander
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c
> > b/drivers/gpu/drm/i915/display/intel_display.c
> > index 2afd10bbe7b8..7c25060e5f32 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -8694,5 +8694,5 @@ void intel_hpd_poll_fini(struct
> > drm_i915_private *i915)
> >  
> >  bool intel_scanout_needs_vtd_wa(struct drm_i915_private *i915)
> >  {
> > -       return DISPLAY_VER(i915) >= 6 && i915_vtd_active(i915);
> > +       return IS_DISPLAY_VER(i915, 6, 11) && i915_vtd_active(i915);
> >  }
> 

-- 
Ville Syrjälä
Intel