[Intel-gfx] [PATCH] drm/i915: Transform WaInPlaceDecompressionHang to a simple reg write

[Mika Kuoppala]

Oscar Mateo <oscar.mateo at intel.com> writes:

> Hey Mika,
>
> Regarding this patch: is there a consensus on where is the most 
> appropriate place to apply workarounds? My understanding is that 
> per-context workarounds (WAS_SET_BIT, etc...) go in 
> xxx_init_workarounds, while those that are needed only during 
> initialization (I915_WRITE) go in xxx_init_clock_gating. But it doesn't 
> look like this general rule is being followed (probably because 
> xxx_init_clock_gating is a very misleading name?).
>
> This has probably been discussed before, so it would be good if we could 
> document the answer somewhere (maybe it already is?).
>

Yep, xxx_init_workarounds for per context. init_clock_gating for
globals.

If I recall init_clock_gating was a just suitable spot wrt
to init/reset to inject globals.

Have we reached the pain treshold and move to genx_workarounds.c
where there are per context and global entries?

-Mika

> Thanks,
>
> Oscar
>
>
>
> On 09/06/2017 02:12 PM, Oscar Mateo wrote:
>> Afaict, GEN9_GAMT_ECO_REG_RW_IA does not live in the context, so writing
>> it on every context creation is overkill (and wrong).
>>
>> Cc: Mika Kuoppala <mika.kuoppala at intel.com>
>> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
>> Signed-off-by: Oscar Mateo <oscar.mateo at intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_engine_cs.c | 25 +++++++++++++++----------
>>   1 file changed, 15 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
>> index 23812ec..9f01a5c 100644
>> --- a/drivers/gpu/drm/i915/intel_engine_cs.c
>> +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
>> @@ -985,8 +985,9 @@ static int skl_init_workarounds(struct intel_engine_cs *engine)
>>   
>>   	/* WaInPlaceDecompressionHang:skl */
>>   	if (IS_SKL_REVID(dev_priv, SKL_REVID_H0, REVID_FOREVER))
>> -		WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
>> -			   GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
>> +		I915_WRITE(GEN9_GAMT_ECO_REG_RW_IA,
>> +			   (I915_READ(GEN9_GAMT_ECO_REG_RW_IA) |
>> +			    GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
>>   
>>   	/* WaDisableLSQCROPERFforOCL:skl */
>>   	ret = wa_ring_whitelist_reg(engine, GEN8_L3SQCREG4);
>> @@ -1059,8 +1060,9 @@ static int bxt_init_workarounds(struct intel_engine_cs *engine)
>>   
>>   	/* WaInPlaceDecompressionHang:bxt */
>>   	if (IS_BXT_REVID(dev_priv, BXT_REVID_C0, REVID_FOREVER))
>> -		WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
>> -			   GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
>> +		I915_WRITE(GEN9_GAMT_ECO_REG_RW_IA,
>> +			   (I915_READ(GEN9_GAMT_ECO_REG_RW_IA) |
>> +			    GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
>>   
>>   	return 0;
>>   }
>> @@ -1089,8 +1091,9 @@ static int cnl_init_workarounds(struct intel_engine_cs *engine)
>>   				  GEN8_CSC2_SBE_VUE_CACHE_CONSERVATIVE);
>>   
>>   	/* WaInPlaceDecompressionHang:cnl */
>> -	WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
>> -		   GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
>> +	I915_WRITE(GEN9_GAMT_ECO_REG_RW_IA,
>> +		   (I915_READ(GEN9_GAMT_ECO_REG_RW_IA) |
>> +		    GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
>>   
>>   	/* WaPushConstantDereferenceHoldDisable:cnl */
>>   	WA_SET_BIT(GEN7_ROW_CHICKEN2, PUSH_CONSTANT_DEREF_DISABLE);
>> @@ -1143,8 +1146,9 @@ static int kbl_init_workarounds(struct intel_engine_cs *engine)
>>   		GEN7_SBE_SS_CACHE_DISPATCH_PORT_SHARING_DISABLE);
>>   
>>   	/* WaInPlaceDecompressionHang:kbl */
>> -	WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
>> -		   GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
>> +	I915_WRITE(GEN9_GAMT_ECO_REG_RW_IA,
>> +		   (I915_READ(GEN9_GAMT_ECO_REG_RW_IA) |
>> +		    GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
>>   
>>   	/* WaDisableLSQCROPERFforOCL:kbl */
>>   	ret = wa_ring_whitelist_reg(engine, GEN8_L3SQCREG4);
>> @@ -1196,8 +1200,9 @@ static int cfl_init_workarounds(struct intel_engine_cs *engine)
>>   		GEN7_SBE_SS_CACHE_DISPATCH_PORT_SHARING_DISABLE);
>>   
>>   	/* WaInPlaceDecompressionHang:cfl */
>> -	WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
>> -		   GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
>> +	I915_WRITE(GEN9_GAMT_ECO_REG_RW_IA,
>> +		   (I915_READ(GEN9_GAMT_ECO_REG_RW_IA) |
>> +		    GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
>>   
>>   	return 0;
>>   }
>
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