On 26/04/2016 10:11, Peter Antoine wrote:
> This patch resizes the GuC WOPCM to so that the GuC and the RC6 memory
> spaces do not overlap.
>
> Issue: https://jira01.devtools.intel.com/browse/VIZ-6638
> Signed-off-by: Peter Antoine <peter.antoine@intel.com>
> ---
>   drivers/gpu/drm/i915/i915_guc_reg.h     | 5 +++--
>   drivers/gpu/drm/i915/intel_guc_loader.c | 6 +++++-
>   2 files changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_guc_reg.h b/drivers/gpu/drm/i915/i915_guc_reg.h
> index 80786d9..6e01238 100644
> --- a/drivers/gpu/drm/i915/i915_guc_reg.h
> +++ b/drivers/gpu/drm/i915/i915_guc_reg.h
> @@ -68,10 +68,11 @@
>   #define GUC_MAX_IDLE_COUNT		_MMIO(0xC3E4)
>   
>   #define GUC_WOPCM_SIZE			_MMIO(0xc050)
> -#define   GUC_WOPCM_SIZE_VALUE  	  (0x80 << 12)	/* 512KB */
> +#define   GUC_WOPCM_SIZE_VALUE		(0x80 << 12)	/* 512KB */
> +#define   BXT_GUC_WOPCM_SIZE_VALUE	(0x70 << 12)	/* 448KB */
>   
>   /* GuC addresses below GUC_WOPCM_TOP don't map through the GTT */
> -#define	GUC_WOPCM_TOP			(GUC_WOPCM_SIZE_VALUE)
> +#define	GUC_WOPCM_TOP			(0x80 << 12)	/* 512KB */
>   
>   #define GEN8_GT_PM_CONFIG		_MMIO(0x138140)
>   #define GEN9LP_GT_PM_CONFIG		_MMIO(0x138140)
> diff --git a/drivers/gpu/drm/i915/intel_guc_loader.c b/drivers/gpu/drm/i915/intel_guc_loader.c
> index fc3ff68..38fb321 100644
> --- a/drivers/gpu/drm/i915/intel_guc_loader.c
> +++ b/drivers/gpu/drm/i915/intel_guc_loader.c
> @@ -312,7 +312,11 @@ static int guc_ucode_xfer(struct drm_i915_private *dev_priv)
>   	intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
>   
>   	/* init WOPCM */
> -	I915_WRITE(GUC_WOPCM_SIZE, GUC_WOPCM_SIZE_VALUE);
> +	if (IS_BROXTON(dev))
> +		I915_WRITE(GUC_WOPCM_SIZE, BXT_GUC_WOPCM_SIZE_VALUE);
> +	else
> +		I915_WRITE(GUC_WOPCM_SIZE, GUC_WOPCM_SIZE_VALUE);
> +
>   	I915_WRITE(DMA_GUC_WOPCM_OFFSET, GUC_WOPCM_OFFSET_VALUE);
>   
>   	/* Enable MIA caching. GuC clock gating is disabled. */

So, this gives the right result, but doesn't really show or explain why 
we have different values, or how the values are arrived at; they're just 
more magic numbers. Also, in the loader there's a check on the firmware 
size that uses different values. So I'd rather prefer the unified 
approach in the attached version ...

.Dave.