Re: [PATCH] drm/i915: enable HiZ Raw Stall Optimization

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

On Mon, Jan 27, 2014 at 04:18:36PM +0800, Chia-I Wu wrote:
> From: Chia-I Wu <olv@lunarg.com>
> 
> The optimization is available on Ivy Bridge and later, and is disabled by
> default.  Enabling it helps certain workloads such as GLBenchmark TRex test.

Actually BSpec even goes as far as saying that this optimization must
be enabled on HSW+.

So it seems you should enable it for BDW as well. I'm not sure about VLV.
The description of the bit says nothing about VLV, even though the
documented default value is specified to have it set for VLV as well. I
guess someone should just try it and see what happens.

Might make sense to split the patch into per-platforms patches. That way
we could more easily revert eg. just the IVB part if it causes problems.

> 
> Signed-off-by: Chia-I Wu <olv@lunarg.com>
> Cc: Ian Romanick <ian.d.romanick@intel.com>
> Cc: Chad Versace <chad.versace@linux.intel.com>
> 
> ---
>  drivers/gpu/drm/i915/i915_reg.h     | 2 ++
>  drivers/gpu/drm/i915/i915_suspend.c | 9 +++++++--
>  drivers/gpu/drm/i915/intel_pm.c     | 8 ++++++++
>  3 files changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index ee27421..bd90ef3 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -930,6 +930,8 @@
>  #define   ECO_GATING_CX_ONLY	(1<<3)
>  #define   ECO_FLIP_DONE		(1<<0)
>  
> +#define CACHE_MODE_0_GEN7	0x7000 /* IVB+ */
> +#define   HIZ_RAW_STALL_OPT_DISABLE (1<<2)
>  #define CACHE_MODE_1		0x7004 /* IVB+ */
>  #define   PIXEL_SUBSPAN_COLLECT_OPT_DISABLE (1<<6)
>  
> diff --git a/drivers/gpu/drm/i915/i915_suspend.c b/drivers/gpu/drm/i915/i915_suspend.c
> index 98790c7..13fefbd 100644
> --- a/drivers/gpu/drm/i915/i915_suspend.c
> +++ b/drivers/gpu/drm/i915/i915_suspend.c
> @@ -398,7 +398,9 @@ int i915_save_state(struct drm_device *dev)
>  	intel_disable_gt_powersave(dev);
>  
>  	/* Cache mode state */
> -	if (INTEL_INFO(dev)->gen < 7)
> +	if (INTEL_INFO(dev)->gen >= 7)
> +		dev_priv->regfile.saveCACHE_MODE_0 = I915_READ(CACHE_MODE_0_GEN7);
> +	else
>  		dev_priv->regfile.saveCACHE_MODE_0 = I915_READ(CACHE_MODE_0);
>  
>  	/* Memory Arbitration state */
> @@ -448,7 +450,10 @@ int i915_restore_state(struct drm_device *dev)
>  	}
>  
>  	/* Cache mode state */
> -	if (INTEL_INFO(dev)->gen < 7)
> +	if (INTEL_INFO(dev)->gen >= 7)
> +		I915_WRITE(CACHE_MODE_0_GEN7, dev_priv->regfile.saveCACHE_MODE_0 |
> +			   0xffff0000);
> +	else
>  		I915_WRITE(CACHE_MODE_0, dev_priv->regfile.saveCACHE_MODE_0 |
>  			   0xffff0000);

These hunks are material for a separate patch.

>  
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 26c29c1..d6ddc39 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -5355,6 +5355,10 @@ static void haswell_init_clock_gating(struct drm_device *dev)
>  	/* WaVSRefCountFullforceMissDisable:hsw */
>  	gen7_setup_fixed_func_scheduler(dev_priv);
>  
> +	/* enable HiZ Raw Stall Optimization */
> +	I915_WRITE(CACHE_MODE_0_GEN7,
> +		   _MASKED_BIT_DISABLE(HIZ_RAW_STALL_OPT_DISABLE));
> +
>  	/* WaDisable4x2SubspanOptimization:hsw */
>  	I915_WRITE(CACHE_MODE_1,
>  		   _MASKED_BIT_ENABLE(PIXEL_SUBSPAN_COLLECT_OPT_DISABLE));
> @@ -5445,6 +5449,10 @@ static void ivybridge_init_clock_gating(struct drm_device *dev)
>  	/* WaVSRefCountFullforceMissDisable:ivb */
>  	gen7_setup_fixed_func_scheduler(dev_priv);
>  
> +	/* enable HiZ Raw Stall Optimization */
> +	I915_WRITE(CACHE_MODE_0_GEN7,
> +		   _MASKED_BIT_DISABLE(HIZ_RAW_STALL_OPT_DISABLE));
> +
>  	/* WaDisable4x2SubspanOptimization:ivb */
>  	I915_WRITE(CACHE_MODE_1,
>  		   _MASKED_BIT_ENABLE(PIXEL_SUBSPAN_COLLECT_OPT_DISABLE));
> -- 
> 1.8.5.3
> 
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-- 
Ville Syrjälä
Intel OTC