[Intel-gfx] [PATCH] drm/i915/cnl: WaThrottleEUPerfToAvoidTDBackPressure:cnl(pre-prod)

[Rodrigo Vivi]

On Wed, Sep 6, 2017 at 3:03 PM, Rodrigo Vivi <rodrigo.vivi at intel.com> wrote:
> Wa for B-stepping only.
>
> A for a hang issue that requires throttling EU performace
> to 12.5% to avoid back pressure to thread dispatch
>
> v2: Rebased. No change from v1.
>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Reviewed-by: Oscar Mateo <oscar.mateo at intel.com>

merged to dinq. thanks for reviewing it.

> ---
>  drivers/gpu/drm/i915/i915_reg.h        | 1 +
>  drivers/gpu/drm/i915/intel_engine_cs.c | 4 ++++
>  2 files changed, 5 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 5651081ff789..8f3645cd8370 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -8058,6 +8058,7 @@ enum {
>  #define   FLOW_CONTROL_ENABLE          (1<<15)
>  #define   PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE        (1<<8)
>  #define   STALL_DOP_GATING_DISABLE             (1<<5)
> +#define   THROTTLE_12_5                                (7<<2)
>
>  #define GEN7_ROW_CHICKEN2              _MMIO(0xe4f4)
>  #define GEN7_ROW_CHICKEN2_GT2          _MMIO(0xf4f4)
> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> index 23812ec23969..b8e9a234af2d 100644
> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> @@ -1079,6 +1079,10 @@ static int cnl_init_workarounds(struct intel_engine_cs *engine)
>         WA_SET_BIT_MASKED(CNL_HDC_CHICKEN0,
>                           HDC_FORCE_CONTEXT_SAVE_RESTORE_NON_COHERENT);
>
> +       /* WaThrottleEUPerfToAvoidTDBackPressure:cnl(pre-prod) */
> +       if (IS_CNL_REVID(dev_priv, CNL_REVID_B0, CNL_REVID_B0))
> +               WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN, THROTTLE_12_5);
> +
>         /* WaDisableReplayBufferBankArbitrationOptimization:cnl */
>         WA_SET_BIT_MASKED(COMMON_SLICE_CHICKEN2,
>                           GEN8_SBE_DISABLE_REPLAY_BUF_OPTIMIZATION);
> --
> 2.13.2
>
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-- 
Rodrigo Vivi
Blog: http://blog.vivi.eng.br