Re: [Intel-gfx] [PATCH] drm/i915: Disable SAMPLER_STATE prefetching on all Gen11 steppings.

[Mika Kuoppala <mika.kuoppala@linux.intel.com>]

Chris Wilson <chris@chris-wilson.co.uk> writes:

> From: Kenneth Graunke <kenneth@whitecape.org>
>
> The Demand Prefetch workaround (binding table prefetching) only applies
> to Icelake A0/B0.  But the Sampler Prefetch workaround needs to be
> applied to all Gen11 steppings, according to a programming note in the
> SARCHKMD documentation.
>
> Using the Intel Gallium driver, I have seen intermittent failures in
> the dEQP-GLES31.functional.copy_image.non_compressed.* tests.  After
> applying this workaround, the tests reliably pass.
>
> v2: Remove the overlap with a pre-production w/a
>
> BSpec: 9663
> Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: stable@vger.kernel.org

Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/gt/intel_workarounds.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> index c70445adfb02..993804d09517 100644
> --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> @@ -1252,8 +1252,12 @@ rcs_engine_wa_init(struct intel_engine_cs *engine, struct i915_wa_list *wal)
>  		if (IS_ICL_REVID(i915, ICL_REVID_A0, ICL_REVID_B0))
>  			wa_write_or(wal,
>  				    GEN7_SARCHKMD,
> -				    GEN7_DISABLE_DEMAND_PREFETCH |
> -				    GEN7_DISABLE_SAMPLER_PREFETCH);
> +				    GEN7_DISABLE_DEMAND_PREFETCH);
> +
> +		/* Wa_1606682166:icl */
> +		wa_write_or(wal,
> +			    GEN7_SARCHKMD,
> +			    GEN7_DISABLE_SAMPLER_PREFETCH);
>  	}
>  
>  	if (IS_GEN_RANGE(i915, 9, 11)) {
> -- 
> 2.20.1
>
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