[Intel-gfx] [PATCH v2 05/10] drm/i915/bdw: Remove WaDisableThreadStallDopClockGating

[Arun Siluvery]

On 28/09/2015 09:44, Jani Nikula wrote:
> On Fri, 25 Sep 2015, Arun Siluvery <arun.siluvery at linux.intel.com> wrote:
>> Dropping it because it is for pre-production stepping.
>
> Hum, why have we added a pre-pro w/a without a stepping check... should
> we backport this to stable kernels? What's the impact on production
> hardware with vs. without the w/a?

The original patch that added pre-production comment is very old.

commit 101b376d358e2f724db5e0ac4d207079b16c4754
Author: Rodrigo Vivi <rodrigo.vivi at intel.com>
Date:   Thu Oct 9 07:11:47 2014 -0700

     drm/i915/bdw: Remove BDW preproduction W/As until C stepping.

     Let's clean this a bit

     v2: Rebase after other Mika's patch that removed some BDW 
production workarounds.
     v3: Removed stepping info.


For BDW it is only applicable UNTIL_D0. According to hsd it is related 
to a hang in emulation but I am checking with HW team to understand its 
impact (if any) better in production steppings.

regards
Arun

>
> BR,
> Jani.
>
>
>>
>> Signed-off-by: Arun Siluvery <arun.siluvery at linux.intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_ringbuffer.c | 3 ---
>>   1 file changed, 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
>> index d8fa9d1..0b545cf 100644
>> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
>> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
>> @@ -827,9 +827,6 @@ static int bdw_init_workarounds(struct intel_engine_cs *ring)
>>   	if (ret)
>>   		return ret;
>>
>> -	/* WaDisableThreadStallDopClockGating:bdw (pre-production) */
>> -	WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN, STALL_DOP_GATING_DISABLE);
>> -
>>   	/* WaDisableDopClockGating:bdw */
>>   	WA_SET_BIT_MASKED(GEN7_ROW_CHICKEN2,
>>   			  DOP_CLOCK_GATING_DISABLE);
>> --
>> 1.9.1
>>
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>