Re: [PATCH v2] drm/i915/display: update handling of FBC when VT-d active workaround

["Govindapillai, Vinod" <vinod.govindapillai@intel.com>]

On Tue, 2024-05-28 at 14:19 +0300, Jani Nikula wrote:
> On Tue, 28 May 2024, Vinod Govindapillai <vinod.govindapillai@intel.com> wrote:
> > Move the handling of the disabling FBC when VT-d is active wa
> > as part of the intel_fbc_check_plane(). As the hw is still there,
> > intel_fbc_sanitize should be able to handle the state properly.
> > 
> > v2: update the patch description (Jani Nikula)
> > 
> > Bspec: 21664
> > Suggested-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_fbc.c | 22 ++++++----------------
> >  1 file changed, 6 insertions(+), 16 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
> > index e9189a864f69..492dc26ecfa2 100644
> > --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> > +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> > @@ -1235,6 +1235,12 @@ static int intel_fbc_check_plane(struct intel_atomic_state *state,
> >                 return 0;
> >         }
> >  
> > +       /* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */
> > +       if (i915_vtd_active(i915) && (IS_SKYLAKE(i915) || IS_BROXTON(i915))) {
> > +               plane_state->no_fbc_reason = "VT-d enabled";
> > +               return true;
> 
> Sorry for only glancing at the commit message first time around.
> 
> This one here returns true from a function that uses int error codes and
> 0 means success. And the 1 is interpreted as an error.
> 
> BR,
> Jani.

ah..:( Thanks for noticing that! Copy paste mistake :(

BR
Vinod

> 
> > +       }
> > +
> >         crtc_state = intel_atomic_get_new_crtc_state(state, crtc);
> >  
> >         if (crtc_state->hw.adjusted_mode.flags & DRM_MODE_FLAG_INTERLACE) {
> > @@ -1820,19 +1826,6 @@ static int intel_sanitize_fbc_option(struct drm_i915_private *i915)
> >         return 0;
> >  }
> >  
> > -static bool need_fbc_vtd_wa(struct drm_i915_private *i915)
> > -{
> > -       /* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */
> > -       if (i915_vtd_active(i915) &&
> > -           (IS_SKYLAKE(i915) || IS_BROXTON(i915))) {
> > -               drm_info(&i915->drm,
> > -                        "Disabling framebuffer compression (FBC) to prevent screen flicker with
> > VT-d enabled\n");
> > -               return true;
> > -       }
> > -
> > -       return false;
> > -}
> > -
> >  void intel_fbc_add_plane(struct intel_fbc *fbc, struct intel_plane *plane)
> >  {
> >         plane->fbc = fbc;
> > @@ -1878,9 +1871,6 @@ void intel_fbc_init(struct drm_i915_private *i915)
> >  {
> >         enum intel_fbc_id fbc_id;
> >  
> > -       if (need_fbc_vtd_wa(i915))
> > -               DISPLAY_RUNTIME_INFO(i915)->fbc_mask = 0;
> > -
> >         i915->display.params.enable_fbc = intel_sanitize_fbc_option(i915);
> >         drm_dbg_kms(&i915->drm, "Sanitized enable_fbc value: %d\n",
> >                     i915->display.params.enable_fbc);
>