[PATCH v2] drm/amdgpu: fix solid screen and hard hang when 2k + 4k display connected with DP

[Deucher, Alexander]

> -----Original Message-----
> From: Huang Rui [mailto:ray.huang at amd.com]
> Sent: Monday, June 26, 2017 8:18 AM
> To: amd-gfx at lists.freedesktop.org; Deucher, Alexander; Koenig, Christian
> Cc: Wang, Ken; Qiao, Joe(Markham); Jiang, Sonny; Huan, Alvin; Huang, Ray
> Subject: [PATCH v2] drm/amdgpu: fix solid screen and hard hang when 2k +
> 4k display connected with DP
> 
> Signed-off-by: Huang Rui <ray.huang at amd.com>

Acked-by: Alex Deucher <alexander.deucher at amd.com>

> ---
> 
> V1 -> V2:
> - Add READ_ONCE to avoid complier might cause to read as previous fence
> value.
> 
> I will refine fence checking with fence interface at amdgpu_fence.c after S3
> stress issue completed as Christian's suggestion.
> 
> Thanks,
> Ray
> 
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
> index 5bed483..af3c87b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.c
> @@ -130,7 +130,7 @@ psp_cmd_submit_buf(struct psp_context *psp,
>  	ret = psp_cmd_submit(psp, ucode, cmd_buf_mc_addr,
>  			     fence_mc_addr, index);
> 
> -	while (*((unsigned int *)psp->fence_buf) != index) {
> +	while (READ_ONCE(*((unsigned int *)psp->fence_buf)) < index) {
>  		msleep(1);
>  	}
> 
> --
> 2.7.4