[PATCH] drm/amdgpu: fix sdma v4 ring is disabled accidently

[Koenig, Christian]

Mhm, good catch.

And yes using the paging queue when it is available sounds like a good 
idea to me as well.

So far I've only used it for VM updates to actually test if it works as 
expected.

Regards,
Christian.

Am 19.10.18 um 21:53 schrieb Kuehling, Felix:
> [+Christian]
>
> Should the buffer funcs also use the paging ring? I think that would be
> important for being able to clear page tables or migrating a BO while
> handling a page fault.
>
> Regards,
>    Felix
>
> On 2018-10-19 3:13 p.m., Yang, Philip wrote:
>> For sdma v4, there is bug caused by
>> commit d4e869b6b5d6 ("drm/amdgpu: add ring test for page queue")'
>>
>> local variable ring is reused and changed, so amdgpu_ttm_set_buffer_funcs_status(adev, true)
>> is skipped accidently. As a result, amdgpu_fill_buffer() will fail, kernel message:
>>
>> [drm:amdgpu_fill_buffer [amdgpu]] *ERROR* Trying to clear memory with ring turned off.
>> [   25.260444] [drm:amdgpu_fill_buffer [amdgpu]] *ERROR* Trying to clear memory with ring turned off.
>> [   25.260627] [drm:amdgpu_fill_buffer [amdgpu]] *ERROR* Trying to clear memory with ring turned off.
>> [   25.290119] [drm:amdgpu_fill_buffer [amdgpu]] *ERROR* Trying to clear memory with ring turned off.
>> [   25.290370] [drm:amdgpu_fill_buffer [amdgpu]] *ERROR* Trying to clear memory with ring turned off.
>> [   25.319971] [drm:amdgpu_fill_buffer [amdgpu]] *ERROR* Trying to clear memory with ring turned off.
>> [   25.320486] amdgpu 0000:19:00.0: [mmhub] VMC page fault (src_id:0 ring:154 vmid:8 pasid:32768, for process  pid 0 thread  pid 0)
>> [   25.320533] amdgpu 0000:19:00.0:   in page starting at address 0x0000000000000000 from 18
>> [   25.320563] amdgpu 0000:19:00.0: VM_L2_PROTECTION_FAULT_STATUS:0x00800134
>>
>> Change-Id: Idacdf8e60557edb0a4a499aa4051b75d87ce4091
>> Signed-off-by: Philip Yang <Philip.Yang at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c | 7 ++++---
>>   1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c b/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
>> index ede149a..cd368ac 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
>> @@ -1151,10 +1151,11 @@ static int sdma_v4_0_start(struct amdgpu_device *adev)
>>   		}
>>   
>>   		if (adev->sdma.has_page_queue) {
>> -			ring = &adev->sdma.instance[i].page;
>> -			r = amdgpu_ring_test_ring(ring);
>> +			struct amdgpu_ring *page = &adev->sdma.instance[i].page;
>> +
>> +			r = amdgpu_ring_test_ring(page);
>>   			if (r) {
>> -				ring->ready = false;
>> +				page->ready = false;
>>   				return r;
>>   			}
>>   		}