[PATCH] drm/amdgpu: Clean sdma wptr register when only enable wptr polling

[Yu, Xiangliang]

Better to add comment above the code.

Reviewed-by: Xiangliang Yu <Xiangliang.Yu at amd.com>


> -----Original Message-----
> From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On Behalf
> Of Emily Deng
> Sent: Tuesday, March 06, 2018 5:17 PM
> To: amd-gfx at lists.freedesktop.org
> Cc: Deng, Emily <Emily.Deng at amd.com>
> Subject: [PATCH] drm/amdgpu: Clean sdma wptr register when only enable
> wptr polling
> 
> The sdma wptr polling memory is not fast enough, then the sdma wptr
> register will be random, and not equal to sdma rptr, which will cause sdma
> engine hang when load driver, so clean up the sdma wptr directly to fix this
> issue.
> 
> Signed-off-by: Emily Deng <Emily.Deng at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c
> b/drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c
> index 521978c..2a27928 100644
> --- a/drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c
> @@ -719,11 +719,12 @@ static int sdma_v3_0_gfx_resume(struct
> amdgpu_device *adev)
>  		WREG32(mmSDMA0_GFX_RB_WPTR_POLL_ADDR_HI +
> sdma_offsets[i],
>  		       upper_32_bits(wptr_gpu_addr));
>  		wptr_poll_cntl =
> RREG32(mmSDMA0_GFX_RB_WPTR_POLL_CNTL + sdma_offsets[i]);
> -		if (ring->use_pollmem)
> +		if (ring->use_pollmem) {
> +			WREG32(mmSDMA0_GFX_RB_WPTR +
> sdma_offsets[i], 0);
>  			wptr_poll_cntl = REG_SET_FIELD(wptr_poll_cntl,
> 
> SDMA0_GFX_RB_WPTR_POLL_CNTL,
>  						       ENABLE, 1);
> -		else
> +		} else
>  			wptr_poll_cntl = REG_SET_FIELD(wptr_poll_cntl,
> 
> SDMA0_GFX_RB_WPTR_POLL_CNTL,
>  						       ENABLE, 0);
> --
> 2.7.4
> 
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