Re: [PATCH] drm/amdgpu: skip IB tests for KIQ in general

["S, Shirish" <sshankar-5C7GfCeVMHo@public.gmane.org>]

On 10/4/2018 12:41 PM, Christian König wrote:
> Am 03.10.2018 um 17:15 schrieb Shirish S:
>> From: Pratik Vishwakarma <Pratik.Vishwakarma@amd.com>
>>
>> [Why]
>> 1. We never submit IBs to KIQ.
>> 2. Ring test pass without KIQ's ring also.
>> 3. By skipping we see an improvement of around 500ms
>>     in the amdgpu's resume time.
>>
>> [How]
>> skip IB tests for KIQ ring type.
>>
>> Signed-off-by: Shirish S <shirish.s@amd.com>
>> Signed-off-by: Pratik Vishwakarma <Pratik.Vishwakarma@amd.com>
>
> Well I'm not sure if that is a good idea or not.
>
> On the one hand it is true that we never submit IBs to the KIQ, so 
> testing that doesn't make much sense actually.
>
> But on the other hand the 500ms delay during resume points out a 
> problem with the KIQ, e.g. interrupts are not working correctly!
>
> Question is now if we should ignore that problem because we never use 
> interrupts on the KIQ?
>
Yes Christian,  that's the approach as no point fixing something we 
never use.
> If the answer is to keep it as it is we should remove the intterupt 
> handling for the KIQ as well.
>
I have sent a patch that shall remove interrupt handling for KIQ, please 
review.

Regards,
Shirish S
> Otherwise I would say we should fix interrupts on the KIQ and then we 
> also don't need this change any more.
>
> Regards,
> Christian.
>
>> ---
>>
>> This patch is a follow-up to the suggestion given by Alex,
>> while reviewing the patch: 
>> https://patchwork.freedesktop.org/patch/250912/
>>
>> -Shirish S
>>
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
>> index 47817e0..b8963b7 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
>> @@ -354,6 +354,14 @@ int amdgpu_ib_ring_tests(struct amdgpu_device 
>> *adev)
>>           if (!ring || !ring->ready)
>>               continue;
>>   +        /* skip IB tests for KIQ in general for the below reasons:
>> +         * 1. We never submit IBs to the KIQ
>> +         * 2. KIQ doesn't use the EOP interrupts,
>> +         *    we use some other CP interrupt.
>> +         */
>> +        if (ring->funcs->type == AMDGPU_RING_TYPE_KIQ)
>> +            continue;
>> +
>>           /* MM engine need more time */
>>           if (ring->funcs->type == AMDGPU_RING_TYPE_UVD ||
>>               ring->funcs->type == AMDGPU_RING_TYPE_VCE ||
>

-- 
Regards,
Shirish S

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