Re: [PATCH] drm/i915/cnl: WaForceContextSaveRestoreNonCoherent

[Oscar Mateo <oscar.mateo@intel.com>]

On 08/22/2017 04:27 PM, Rodrigo Vivi wrote:
> To avoid a potential hang condition with TLB invalidation
> we need to enable masked bit 5 of MMIO 0xE5F0 at boot.
>
> Same workaround was in place for previous platforms,
> but the change for CNL is more on the register offset.

"but the register offset has changed for CNL"?

> But also BSpec doesn't mention the bit 15 as set on gen9
> platforms and mark bit as reserved on CNL.
>
> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
> Cc: Oscar Mateo <oscar.mateo@intel.com>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> ---
>   drivers/gpu/drm/i915/i915_reg.h        | 1 +
>   drivers/gpu/drm/i915/intel_engine_cs.c | 4 ++++
>   2 files changed, 5 insertions(+)

Reviewed-by: Oscar Mateo <oscar.mateo@intel.com>

> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index d4ecb1905ad8..f31fab2651fb 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -7024,6 +7024,7 @@ enum {
>   
>   /* GEN8 chicken */
>   #define HDC_CHICKEN0				_MMIO(0x7300)
> +#define CNL_HDC_CHICKEN0			_MMIO(0xE5F0)
>   #define  HDC_FORCE_CSR_NON_COHERENT_OVR_DISABLE	(1<<15)
>   #define  HDC_FENCE_DEST_SLM_DISABLE		(1<<14)
>   #define  HDC_DONOT_FETCH_MEM_WHEN_MASKED	(1<<11)
> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> index d23f18874309..26c35ce5f240 100644
> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> @@ -1070,6 +1070,10 @@ static int cnl_init_workarounds(struct intel_engine_cs *engine)
>   	struct drm_i915_private *dev_priv = engine->i915;
>   	int ret;
>   
> +	/* WaForceContextSaveRestoreNonCoherent:cnl */
> +	WA_SET_BIT_MASKED(CNL_HDC_CHICKEN0,
> +			  HDC_FORCE_CONTEXT_SAVE_RESTORE_NON_COHERENT);
> +
>   	/* WaDisableReplayBufferBankArbitrationOptimization:cnl */
>   	WA_SET_BIT_MASKED(COMMON_SLICE_CHICKEN2,
>   			  GEN8_SBE_DISABLE_REPLAY_BUF_OPTIMIZATION);

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