[Intel-gfx] [PATCH] drm/i915/pvc: Add recommended MMIO setting

[Souza, Jose]

On Mon, 2022-06-13 at 09:53 -0700, Matt Roper wrote:
> As with past platforms, the bspec's performance tuning guide provides
> recommended MMIO settings.  Although not technically "workarounds" we
> apply these through the workaround framework to ensure that they're
> re-applied at the proper times (e.g., on engine resets) and that any
> conflicts with real workarounds are flagged.

Reviewed-by: José Roberto de Souza <jose.souza at intel.com>

> 
> Bspec: 72161
> Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
> ---
>  drivers/gpu/drm/i915/gt/intel_gt_regs.h     | 5 +++++
>  drivers/gpu/drm/i915/gt/intel_workarounds.c | 9 +++++++++
>  2 files changed, 14 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_regs.h b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
> index 226557018037..07ef111947b8 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_regs.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
> @@ -981,6 +981,11 @@
>  #define XEHP_L3SCQREG7				_MMIO(0xb188)
>  #define   BLEND_FILL_CACHING_OPT_DIS		REG_BIT(3)
>  
> +#define XEHPC_L3SCRUB				_MMIO(0xb18c)
> +#define   SCRUB_CL_DWNGRADE_SHARED		REG_BIT(12)
> +#define   SCRUB_RATE_PER_BANK_MASK		REG_GENMASK(2, 0)
> +#define   SCRUB_RATE_4B_PER_CLK			REG_FIELD_PREP(SCRUB_RATE_PER_BANK_MASK, 0x6)
> +
>  #define L3SQCREG1_CCS0				_MMIO(0xb200)
>  #define   FLUSHALLNONCOH			REG_BIT(5)
>  
> diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> index 1e982ac931dc..c4af51144216 100644
> --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> @@ -2679,6 +2679,15 @@ general_render_compute_wa_init(struct intel_engine_cs *engine, struct i915_wa_li
>  {
>  	struct drm_i915_private *i915 = engine->i915;
>  
> +	if (IS_PONTEVECCHIO(i915)) {
> +		/*
> +		 * The following is not actually a "workaround" but rather
> +		 * a recommended tuning setting documented in the bspec's
> +		 * performance guide section.
> +		 */
> +		wa_write(wal, XEHPC_L3SCRUB, SCRUB_CL_DWNGRADE_SHARED | SCRUB_RATE_4B_PER_CLK);
> +	}
> +
>  	if (IS_XEHPSDV(i915)) {
>  		/* Wa_1409954639 */
>  		wa_masked_en(wal,