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

[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;
>  			}
>  		}