[Intel-gfx] [PATCH v3] drm/i915/dg2: Add performance workaround 18019455067

[Lionel Landwerlin]

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On 30/06/2022 11:35, Lionel Landwerlin wrote:
> The recommended number of stackIDs for Ray Tracing subsystem is 512
> rather than 2048 (default HW programming).
>
> v2: Move the programming to dg2_ctx_gt_tuning_init() (Lucas)
>
> v3: Move programming to general_render_compute_wa_init() (Matt)
>
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> ---
>   drivers/gpu/drm/i915/gt/intel_gt_regs.h     | 4 ++++
>   drivers/gpu/drm/i915/gt/intel_workarounds.c | 9 +++++++++
>   2 files changed, 13 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_regs.h b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
> index 07ef111947b8c..12fc87b957425 100644
> --- a/drivers/gpu/drm/i915/gt/intel_gt_regs.h
> +++ b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
> @@ -1112,6 +1112,10 @@
>   #define   GEN12_PUSH_CONST_DEREF_HOLD_DIS	REG_BIT(8)
>   
>   #define RT_CTRL					_MMIO(0xe530)
> +#define   RT_CTRL_NUMBER_OF_STACKIDS_MASK	REG_GENMASK(6, 5)
> +#define   NUMBER_OF_STACKIDS_512		2
> +#define   NUMBER_OF_STACKIDS_1024		1
> +#define   NUMBER_OF_STACKIDS_2048		0
>   #define   DIS_NULL_QUERY			REG_BIT(10)
>   
>   #define EU_PERF_CNTL1				_MMIO(0xe558)
> diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> index 3213c593a55f4..ea674e456cd76 100644
> --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
> +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
> @@ -2737,6 +2737,15 @@ general_render_compute_wa_init(struct intel_engine_cs *engine, struct i915_wa_li
>   		wa_write_or(wal, VDBX_MOD_CTRL, FORCE_MISS_FTLB);
>   		wa_write_or(wal, VEBX_MOD_CTRL, FORCE_MISS_FTLB);
>   	}
> +
> +	if (IS_DG2(i915)) {
> +		/* Performance tuning for Ray-tracing */
> +		wa_write_clr_set(wal,
> +				 RT_CTRL,
> +				 RT_CTRL_NUMBER_OF_STACKIDS_MASK,
> +				 REG_FIELD_PREP(RT_CTRL_NUMBER_OF_STACKIDS_MASK,
> +						NUMBER_OF_STACKIDS_512));
> +	}
>   }
>   
>   static void