[Intel-gfx] [PATCH 2/2] drm/i915/mtl: Disable MC6 for MTL A step

[Nilawar, Badal]

Hi Rodrigo,

On 08-03-2023 18:59, Rodrigo Vivi wrote:
> On Wed, Mar 08, 2023 at 03:51:09PM +0530, Badal Nilawar wrote:
>> The Wa_14017073508 require to send Media Busy/Idle mailbox while
>> accessing Media tile. As of now it is getting handled while __gt_unpark,
>> __gt_park. But there are various corner cases where forcewakes are taken
>> without __gt_unpark i.e. without sending Busy Mailbox especially during
>> register reads. Forcewakes are taken without busy mailbox leads to
>> GPU HANG. So bringing mailbox calls under forcewake calls are no feasible
>> option as forcewake calls are atomic and mailbox calls are blocking.
>> The issue already fixed in B step so disabling MC6 on A step and
>> reverting previous commits which handles Wa_14017073508
>>
>> Fixes: 8f70f1ec587d ("drm/i915/mtl: Add Wa_14017073508 for SAMedia")
>> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
>> Signed-off-by: Badal Nilawar <badal.nilawar at intel.com>
> 
> This patch should probably come before the revert itself.
> 
> Reviewed-by: Rodrigo Vivi <rodrigo.vivi at intel.com>

Thanks for RB. I will put this patch before revert.

Regards,
Badal Nilawar
> 
>> ---
>>   drivers/gpu/drm/i915/gt/intel_rc6.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/intel_rc6.c b/drivers/gpu/drm/i915/gt/intel_rc6.c
>> index 5c91622dfca4..f4150f61f39c 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_rc6.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_rc6.c
>> @@ -486,6 +486,7 @@ static bool bxt_check_bios_rc6_setup(struct intel_rc6 *rc6)
>>   static bool rc6_supported(struct intel_rc6 *rc6)
>>   {
>>   	struct drm_i915_private *i915 = rc6_to_i915(rc6);
>> +	struct intel_gt *gt = rc6_to_gt(rc6);
>>   
>>   	if (!HAS_RC6(i915))
>>   		return false;
>> @@ -502,6 +503,13 @@ static bool rc6_supported(struct intel_rc6 *rc6)
>>   		return false;
>>   	}
>>   
>> +	if (IS_MTL_MEDIA_STEP(gt->i915, STEP_A0, STEP_B0) &&
>> +	    gt->type == GT_MEDIA) {
>> +		drm_notice(&i915->drm,
>> +			   "Media RC6 disabled on A step\n");
>> +		return false;
>> +	}
>> +
>>   	return true;
>>   }
>>   
>> -- 
>> 2.25.1
>>