[Intel-gfx] [PATCH] drm/i915/cnl: WaPushConstantDereferenceHoldDisable

[Vivi, Rodrigo]

On Tue, 2017-08-22 at 15:15 -0700, Oscar Mateo wrote:
> Disable deref enhancement logic.

Could we add a bit more of info here?

like that fixes some CS hangs on 3D Push Constant dispatches?

with a bit more info feel free to add

Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

I checked the spec and chicken reg. Also this Wa was on my todo list
here to try it out.

> 
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> Signed-off-by: Oscar Mateo <oscar.mateo at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_reg.h        | 1 +
>  drivers/gpu/drm/i915/intel_engine_cs.c | 3 +++
>  2 files changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index d4ecb19..d9b0249 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -8055,6 +8055,7 @@ enum {
>  #define GEN7_ROW_CHICKEN2		_MMIO(0xe4f4)
>  #define GEN7_ROW_CHICKEN2_GT2		_MMIO(0xf4f4)
>  #define   DOP_CLOCK_GATING_DISABLE	(1<<0)
> +#define   PUSH_CONSTANT_DEREF_DISABLE	(1<<8)
>  
>  #define HSW_ROW_CHICKEN3		_MMIO(0xe49c)
>  #define  HSW_ROW_CHICKEN3_L3_GLOBAL_ATOMICS_DISABLE    (1 << 6)
> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> index d23f188..d7e1ccf 100644
> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> @@ -1083,6 +1083,9 @@ static int cnl_init_workarounds(struct intel_engine_cs *engine)
>  	WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
>  		   GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
>  
> +	/* WaPushConstantDereferenceHoldDisable:cnl */
> +	WA_SET_BIT(GEN7_ROW_CHICKEN2, PUSH_CONSTANT_DEREF_DISABLE);
> +
>  	/* WaEnablePreemptionGranularityControlByUMD:cnl */
>  	ret= wa_ring_whitelist_reg(engine, GEN8_CS_CHICKEN1);
>  	if (ret)