Re: [Intel-gfx] [PATCH] drm/i915/dg2: Return Wa_22012654132 to just specific steppings

[Matt Atwood <matthew.s.atwood@intel.com>]

On Tue, Dec 13, 2022 at 03:41:19PM -0800, Matt Roper wrote:
> Programming of the ENABLE_PREFETCH_INTO_IC bit originally showed up in
> both the general DG2 tuning guide (applicable to all DG2
> variants/steppings) and under Wa_22012654132 (applicable only to
> specific steppings).  It has now been removed from the tuning guide, and
> the guidance is to only program it in the specific steppings associated
> with the workaround.
> 
> Bspec: 68331
Reviewed-by: Matt Atwood <matthew.s.atwood@intel.com>
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_workarounds.c | 27 ++++++++++-----------
>  1 file changed, 13 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> index 7d71f5bbddc8..bf84efb3f15f 100644
> --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> @@ -2913,20 +2913,6 @@ add_render_compute_tuning_settings(struct drm_i915_private *i915,
>  	if (IS_DG2(i915)) {
>  		wa_mcr_write_or(wal, XEHP_L3SCQREG7, BLEND_FILL_CACHING_OPT_DIS);
>  		wa_mcr_write_clr_set(wal, RT_CTRL, STACKID_CTRL, STACKID_CTRL_512);
> -
> -		/*
> -		 * This is also listed as Wa_22012654132 for certain DG2
> -		 * steppings, but the tuning setting programming is a superset
> -		 * since it applies to all DG2 variants and steppings.
> -		 *
> -		 * Note that register 0xE420 is write-only and cannot be read
> -		 * back for verification on DG2 (due to Wa_14012342262), so
> -		 * we need to explicitly skip the readback.
> -		 */
> -		wa_mcr_add(wal, GEN10_CACHE_MODE_SS, 0,
> -			   _MASKED_BIT_ENABLE(ENABLE_PREFETCH_INTO_IC),
> -			   0 /* write-only, so skip validation */,
> -			   true);
>  	}
>  
>  	/*
> @@ -3022,6 +3008,19 @@ general_render_compute_wa_init(struct intel_engine_cs *engine, struct i915_wa_li
>  		/* Wa_18017747507:dg2 */
>  		wa_masked_en(wal, VFG_PREEMPTION_CHICKEN, POLYGON_TRIFAN_LINELOOP_DISABLE);
>  	}
> +
> +	if (IS_DG2_GRAPHICS_STEP(i915, G10, STEP_A0, STEP_C0) || IS_DG2_G11(i915))
> +		/*
> +		 * Wa_22012654132
> +		 *
> +		 * Note that register 0xE420 is write-only and cannot be read
> +		 * back for verification on DG2 (due to Wa_14012342262), so
> +		 * we need to explicitly skip the readback.
> +		 */
> +		wa_mcr_add(wal, GEN10_CACHE_MODE_SS, 0,
> +			   _MASKED_BIT_ENABLE(ENABLE_PREFETCH_INTO_IC),
> +			   0 /* write-only, so skip validation */,
> +			   true);
>  }
>  
>  static void
> -- 
> 2.38.1
>