Re: [PATCH] drm/i915/fbc: Apply wa_15018326506

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

On Fri, 2025-11-07 at 12:16 +0200, Jani Nikula wrote:
> On Fri, 07 Nov 2025, Vinod Govindapillai
> <vinod.govindapillai@intel.com> wrote:
> > Disable FBC as part for the wa for the bmg variant
> > 
> > Bspec: 74212
> > Signed-off-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_display_wa.c |  4 ++++
> >  drivers/gpu/drm/i915/display/intel_display_wa.h |  1 +
> >  drivers/gpu/drm/i915/display/intel_fbc.c        | 10 ++++++++++
> >  3 files changed, 15 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_wa.c
> > b/drivers/gpu/drm/i915/display/intel_display_wa.c
> > index c528aaa679ca..ba2272d85a04 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_wa.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display_wa.c
> > @@ -10,6 +10,7 @@
> >  #include "intel_display_core.h"
> >  #include "intel_display_regs.h"
> >  #include "intel_display_wa.h"
> > +#include "intel_step.h"
> >  
> >  static void gen11_display_wa_apply(struct intel_display *display)
> >  {
> > @@ -69,6 +70,9 @@ bool __intel_display_wa(struct intel_display
> > *display, enum intel_display_wa wa,
> >  		return DISPLAY_VER(display) == 13;
> >  	case INTEL_DISPLAY_WA_22014263786:
> >  		return IS_DISPLAY_VERx100(display, 1100, 1400);
> > +	case INTEL_DISPLAY_WA_15018326506:
> > +		return DISPLAY_VERx100(display) == 1401 &&
> > +		       INTEL_DISPLAY_STEP(display) == STEP_C0;
> 
> IS_DISPLAY_VERx100_STEP().

I was looking into the comments for that macro! This wa apply only for
step c0 (as of now)! I wasn't sure what the "until" part could be in
that macro! So what do you suggest for the "until"  STEP_D0 or
STEP_FOREVER in such cases!

BR
Vinod


> 
> >  	default:
> >  		drm_WARN(display->drm, 1, "Missing Wa number:
> > %s\n", name);
> >  		break;
> > diff --git a/drivers/gpu/drm/i915/display/intel_display_wa.h
> > b/drivers/gpu/drm/i915/display/intel_display_wa.h
> > index 3644e8e2b724..f648b00cb97d 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display_wa.h
> > +++ b/drivers/gpu/drm/i915/display/intel_display_wa.h
> > @@ -26,6 +26,7 @@ enum intel_display_wa {
> >  	INTEL_DISPLAY_WA_16025573575,
> >  	INTEL_DISPLAY_WA_14011503117,
> >  	INTEL_DISPLAY_WA_22014263786,
> > +	INTEL_DISPLAY_WA_15018326506,
> >  };
> >  
> >  bool __intel_display_wa(struct intel_display *display, enum
> > intel_display_wa wa, const char *name);
> > diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c
> > b/drivers/gpu/drm/i915/display/intel_fbc.c
> > index a1e3083022ee..16cd99db2978 100644
> > --- a/drivers/gpu/drm/i915/display/intel_fbc.c
> > +++ b/drivers/gpu/drm/i915/display/intel_fbc.c
> > @@ -1521,6 +1521,16 @@ static int intel_fbc_check_plane(struct
> > intel_atomic_state *state,
> >  		return 0;
> >  	}
> >  
> > +	/*
> > +	 * wa_15018326506:
> > +	 * Fixes: Underrun during media decode
> > +	 * Workaround: Do not enable FBC
> > +	 */
> > +	if (intel_display_wa(display, 15018326506)) {
> > +		plane_state->no_fbc_reason = "Wa_15018326506";
> > +		return 0;
> > +	}
> > +
> >  	/* WaFbcTurnOffFbcWhenHyperVisorIsUsed:skl,bxt */
> >  	if (intel_display_vtd_active(display) &&
> >  	    (display->platform.skylake || display-
> > >platform.broxton)) {
>