[PATCH 2/2] drm/amdgpu: fix KIQ ring test fail in TDR of SRIOV

[shaoyunl]

I think amdkfd side depends on this call to stop the user queue, without this call, the user queue can submit to HW during the reset which could cause hang again ...
Do we know the root cause why this function would ruin MEC ? From the logic, I think this function should be called before FLR since we need to disable the user queue submission first.
I remembered the function should use hiq to communicate with HW , shouldn't use kiq to access HW registerm,  has this been changed ?


Regards
shaoyun.liu


On 2019-12-17 5:19 a.m., Monk Liu wrote:
> issues:
> MEC is ruined by the amdkfd_pre_reset after VF FLR done
>
> fix:
> amdkfd_pre_reset() would ruin MEC after hypervisor finished the VF FLR,
> the correct sequence is do amdkfd_pre_reset before VF FLR but there is
> a limitation to block this sequence:
> if we do pre_reset() before VF FLR, it would go KIQ way to do register
> access and stuck there, because KIQ probably won't work by that time
> (e.g. you already made GFX hang)
>
> so the best way right now is to simply remove it.
>
> Signed-off-by: Monk Liu <Monk.Liu at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 --
>   1 file changed, 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 605cef6..ae962b9 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -3672,8 +3672,6 @@ static int amdgpu_device_reset_sriov(struct amdgpu_device *adev,
>   	if (r)
>   		return r;
>   
> -	amdgpu_amdkfd_pre_reset(adev);
> -
>   	/* Resume IP prior to SMC */
>   	r = amdgpu_device_ip_reinit_early_sriov(adev);
>   	if (r)