[PATCH] drm/amdgpu: execute amdgpu_ring_patch_cond_exec() only for valid job

[Christian König]

Am 09.07.2018 um 12:30 schrieb Shirish S:
> issue:
> BUG_ON(ring->ring[offset] != 0x55aa55aa) is hit on resume from
> S3 state.
>
> fix & analysis:
>
> fix is  to check for valid job, which in continuation to the below patch:
> 113890e drm/amdgpu: cond_exec only for schedule with a job
>
> Since cond_exec is not initialised if there is no job,
> 0x55aa55aa is not written to ring, as a result in
> patch_cond_exec callback, BUG_ON is hit where it checks for the
> same 0x55aa55aa value in register.
>
> Signed-off-by: Shirish S <shirish.s at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
> index 31f8170..3381ada 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ib.c
> @@ -249,7 +249,7 @@ int amdgpu_ib_schedule(struct amdgpu_ring *ring, unsigned num_ibs,
>   				       fence_flags | AMDGPU_FENCE_FLAG_64BIT);
>   	}
>   
> -	if (patch_offset != ~0 && ring->funcs->patch_cond_exec)
> +	if (job && patch_offset != ~0 && ring->funcs->patch_cond_exec)

NAK, when not patch condition is emitted the patch_offset shouldn't be zero.

So you rational to explain why testing the job doesn't make sense (but 
we could drop testing patch_offset alltogether).

Christian.

>   		amdgpu_ring_patch_cond_exec(ring, patch_offset);
>   
>   	ring->current_ctx = fence_ctx;