[PATCH v3] drm/i915/guc: Simplify/extend platform check for Wa_14018913170

[John Harrison]

On 2/19/2024 12:28, Rodrigo Vivi wrote:
> On Fri, Feb 16, 2024 at 10:38:41AM -0800, John.C.Harrison at Intel.com wrote:
>> From: John Harrison <John.C.Harrison at Intel.com>
>>
>> The above w/a is required for every platform that the i915 driver
>> supports. It is fixed on the latest platforms but they are only
>> supported by Xe instead of i915. So just remove the platform check
>> completely and keep the code simple.
> Well, I was going to say that I would prefer a GMD version greater-than
> check to be future proof. However if this code gets used in some other
> new platform a new specific guc support would likely need to be added
> as well right?
There is no future for i915. That's the point. The only platforms that 
have the hardware fix are all ones that will only ever be supported by 
the Xe driver. So if such a platform were to be backported to i915 then 
there would be a lot more work than just adding a new GuC firmware platform.

And going backwards, the bug affects all platforms that have a GuC. So 
if any GuC code is being executed at all, then this w/a is applicable.

>
> Perhaps at least adding a comment in the code?
Such as this?
         /*
          * Wa_14018913170: Applicable to all platforms supported by i915 so
          * don't bother testing for all X/Y/Z platforms explicitly.
          */

John.


>
> with that
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>
>
>
>> Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
>> ---
>>   drivers/gpu/drm/i915/gt/uc/intel_guc.c | 3 +--
>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.c b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
>> index 2b450c43bbd7f..a3662edb42032 100644
>> --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.c
>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.c
>> @@ -321,8 +321,7 @@ static u32 guc_ctl_wa_flags(struct intel_guc *guc)
>>   
>>   	/* Wa_14018913170 */
>>   	if (GUC_FIRMWARE_VER(guc) >= MAKE_GUC_VER(70, 7, 0)) {
>> -		if (IS_DG2(gt->i915) || IS_METEORLAKE(gt->i915) || IS_PONTEVECCHIO(gt->i915))
>> -			flags |= GUC_WA_ENABLE_TSC_CHECK_ON_RC6;
>> +		flags |= GUC_WA_ENABLE_TSC_CHECK_ON_RC6;
>>   	}
>>   
>>   	return flags;
>> -- 
>> 2.43.0
>>