Re: [Intel-gfx] [PATCH] drm/i915: Don't read query SSEU for non-existent slice 0 on old platforms

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Fri, Nov 12, 2021 at 08:01:07AM -0800, Matt Roper wrote:
> Pre-HSW platforms don't use the gt SSEU structures; this means that
> calling intel_sseu_get_subslices() on slice 0 for these platforms will
> trip a GEM_BUG_ON(slice >= sseu->max_slices) warning.
> 
> Let's move the DSS lookup for a DG2 workaround into a helper function
> that will only get called after we've already decided that we're on a
> DG2 platform.
> 
> Fixes: 645cc0b9d972 ("drm/i915/dg2: Add initial gt/ctx/engine workarounds")
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

> ---
>  drivers/gpu/drm/i915/gt/intel_workarounds.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> index 51591119da15..a9727447c037 100644
> --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> @@ -2019,11 +2019,18 @@ engine_fake_wa_init(struct intel_engine_cs *engine, struct i915_wa_list *wal)
>  				    CMD_CCTL_MOCS_OVERRIDE(mocs, mocs));
>  	}
>  }
> +
> +static bool needs_wa_1308578152(struct intel_engine_cs *engine)
> +{
> +	u64 dss_mask = intel_sseu_get_subslices(&engine->gt->info.sseu, 0);
> +
> +	return (dss_mask & GENMASK(GEN_DSS_PER_GSLICE - 1, 0)) == 0;
> +}
> +
>  static void
>  rcs_engine_wa_init(struct intel_engine_cs *engine, struct i915_wa_list *wal)
>  {
>  	struct drm_i915_private *i915 = engine->i915;
> -	u64 dss_mask = intel_sseu_get_subslices(&engine->gt->info.sseu, 0);
>  
>  	if (IS_DG2_GRAPHICS_STEP(engine->i915, G11, STEP_A0, STEP_B0)) {
>  		/* Wa_14013392000:dg2_g11 */
> @@ -2057,7 +2064,7 @@ rcs_engine_wa_init(struct intel_engine_cs *engine, struct i915_wa_list *wal)
>  
>  	/* Wa_1308578152:dg2_g10 when first gslice is fused off */
>  	if (IS_DG2_GRAPHICS_STEP(engine->i915, G10, STEP_B0, STEP_C0) &&
> -	    (dss_mask & GENMASK(GEN_DSS_PER_GSLICE - 1, 0)) == 0) {
> +	    needs_wa_1308578152(engine)) {
>  		wa_masked_dis(wal, GEN12_CS_DEBUG_MODE1_CCCSUNIT_BE_COMMON,
>  			      GEN12_REPLAY_MODE_GRANULARITY);
>  	}
> -- 
> 2.33.0
>