Re: [PATCH 7/7] drm/i915/gen8: Move HiZ RAW stall optimization disable WA to common init fn

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Sep 25, 2015 at 02:23:34PM +0100, Arun Siluvery wrote:
> Signed-off-by: Arun Siluvery <arun.siluvery@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_ringbuffer.c | 25 ++++++++++---------------
>  1 file changed, 10 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
> index c681c66..fdff606 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
> @@ -819,6 +819,16 @@ static int gen8_init_workarounds(struct intel_engine_cs *ring)
>  	/* Wa4x4STCOptimizationDisable:bdw,chv */
>  	WA_SET_BIT_MASKED(CACHE_MODE_1, GEN8_4x4_STC_OPTIMIZATION_DISABLE);
>  
> +	/* From the Haswell PRM, Command Reference: Registers, CACHE_MODE_0:
> +	 * "The Hierarchical Z RAW Stall Optimization allows non-overlapping
> +	 *  polygons in the same 8x4 pixel/sample area to be processed without
> +	 *  stalling waiting for the earlier ones to write to Hierarchical Z
> +	 *  buffer."
> +	 *
> +	 * This optimization is off by default for BDW and CHV; turn it on.
> +	 */
> +	WA_CLR_BIT_MASKED(CACHE_MODE_0_GEN7, HIZ_RAW_STALL_OPT_DISABLE);
> +

Ok, so apart from the threadstall thing the rest looks reasonable.
One request though, can you put w/as into some decent order? I
suggest ordering based on the register, so eg.

instpm
mi_mode
row chicken
half slice chicken
common slice chicken
hdc chicken
cache_mode_0
cache_mode_1
gt_mode

I think that should match reasonably well what we have in most places.
Or you can come up with something better if you wish, as long as the
same/similar registers are grouped decently.

>  	/*
>  	 * BSpec recommends 8x4 when MSAA is used,
>  	 * however in practice 16x4 seems fastest.
> @@ -865,16 +875,6 @@ static int bdw_init_workarounds(struct intel_engine_cs *ring)
>  			  /* WaDisableFenceDestinationToSLM:bdw (pre-prod) */
>  			  (IS_BDW_GT3(dev) ? HDC_FENCE_DEST_SLM_DISABLE : 0));
>  
> -	/* From the Haswell PRM, Command Reference: Registers, CACHE_MODE_0:
> -	 * "The Hierarchical Z RAW Stall Optimization allows non-overlapping
> -	 *  polygons in the same 8x4 pixel/sample area to be processed without
> -	 *  stalling waiting for the earlier ones to write to Hierarchical Z
> -	 *  buffer."
> -	 *
> -	 * This optimization is off by default for Broadwell; turn it on.
> -	 */
> -	WA_CLR_BIT_MASKED(CACHE_MODE_0_GEN7, HIZ_RAW_STALL_OPT_DISABLE);
> -
>  	return 0;
>  }
>  
> @@ -898,11 +898,6 @@ static int chv_init_workarounds(struct intel_engine_cs *ring)
>  			  HDC_FORCE_NON_COHERENT |
>  			  HDC_DONOT_FETCH_MEM_WHEN_MASKED);
>  
> -	/* According to the CACHE_MODE_0 default value documentation, some
> -	 * CHV platforms disable this optimization by default.  Turn it on.
> -	 */
> -	WA_CLR_BIT_MASKED(CACHE_MODE_0_GEN7, HIZ_RAW_STALL_OPT_DISABLE);
> -
>  	/* Improve HiZ throughput on CHV. */
>  	WA_SET_BIT_MASKED(HIZ_CHICKEN, CHV_HZ_8X8_MODE_IN_1X);
>  
> -- 
> 1.9.1
> 
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-- 
Ville Syrjälä
Intel OTC
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