RE: [PATCH 1/2] drm/amdgpu: Add per device sdma_doorbell_range field

["Zeng, Oak" <Oak.Zeng-5C7GfCeVMHo@public.gmane.org>]

Thanks Philip.

For vega10, sdma doorbells are defined to be windows sriov compatible. Two qwords doorbell are defined for each sdma engine. See amdgpu_doorbell.h line 192. So program nbio sdma doorbell routing range to 4 (dwords) is correct. I am not sure why previously the doorbell range was programmed to 2, even though it is defined 4. @Partap Singh Rana, Dhirendra what value windows does host driver program BIF_SDMA0_DOORBELL_RANGE.SIZE for vega10? 

@Deng, Emily I saw previously you changed the vega10 doorbell assignment for sriov. Did you copy the assignment from windows host driver? If yes, I assume windows host should set the bif doorbell range to 4 dwords, according to the assignment. Does changing bif doorbell range to 4 conflict with windows host driver?

People might wonder why programming it to 2 also worked before. The reason is, currently amdgpu only use one sdma ring per sdma engine. So it never used the "HI_PRI" ring and doorbell. Kfd uses two sdma rings per sdma engine, but for the second ring, it uses a doorbell with the same in page offset (0xf0) but mapped to the second doorbell page of the process.

So my understanding is, setting the doorbell range to 4 (see patch 2 of this series) is more consistent and no harm for current usage model. If we use it in the future, it should be fine. But let's see what is the windows host driver setting. 

Regards,
Oak

-----Original Message-----
From: amd-gfx <amd-gfx-bounces@lists.freedesktop.org> On Behalf Of Yang, Philip
Sent: Tuesday, December 18, 2018 9:57 AM
To: Zeng, Oak <Oak.Zeng@amd.com>; amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH 1/2] drm/amdgpu: Add per device sdma_doorbell_range field



On 2018-12-17 9:12 p.m., Zeng, Oak wrote:
> Different ASIC has different sdma doorbell range. Add a per device 
> sdma_doorbell_range field and initialize it.
> 
> Change-Id: Idd980db1a72cfb373e24ac23ba3e48bb329ed4ad
> Signed-off-by: Oak Zeng <Oak.Zeng@amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h | 2 ++
>   drivers/gpu/drm/amd/amdgpu/vega10_reg_init.c | 1 +
>   drivers/gpu/drm/amd/amdgpu/vega20_reg_init.c | 1 +
>   3 files changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h 
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
> index 35a0c05..1cfec06 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
> @@ -72,6 +72,8 @@ struct amdgpu_doorbell_index {
>   		} uvd_vce;
>   	};
>   	uint32_t max_assignment;
> +	/* Per engine SDMA doorbell size in dword */
> +	uint32_t sdma_doorbell_range;
>   };
>   
>   typedef enum _AMDGPU_DOORBELL_ASSIGNMENT diff --git 
> a/drivers/gpu/drm/amd/amdgpu/vega10_reg_init.c 
> b/drivers/gpu/drm/amd/amdgpu/vega10_reg_init.c
> index b75d17b..4b5d60e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/vega10_reg_init.c
> +++ b/drivers/gpu/drm/amd/amdgpu/vega10_reg_init.c
> @@ -83,5 +83,6 @@ void vega10_doorbell_index_init(struct amdgpu_device *adev)
>   	adev->doorbell_index.uvd_vce.vce_ring6_7 = AMDGPU_DOORBELL64_VCE_RING6_7;
>   	/* In unit of dword doorbell */
>   	adev->doorbell_index.max_assignment = 
> AMDGPU_DOORBELL64_MAX_ASSIGNMENT << 1;
> +	adev->doorbell_index.sdma_doorbell_range = 4;
Vega10 doorbell range was 2 dwords (one 64bit doorbell), change to 4 dwords may not work under SRIOV
>   }
>   
> diff --git a/drivers/gpu/drm/amd/amdgpu/vega20_reg_init.c 
> b/drivers/gpu/drm/amd/amdgpu/vega20_reg_init.c
> index 63c542c..53716c5 100644
> --- a/drivers/gpu/drm/amd/amdgpu/vega20_reg_init.c
> +++ b/drivers/gpu/drm/amd/amdgpu/vega20_reg_init.c
> @@ -86,5 +86,6 @@ void vega20_doorbell_index_init(struct amdgpu_device *adev)
>   	adev->doorbell_index.uvd_vce.vce_ring4_5 = AMDGPU_VEGA20_DOORBELL64_VCE_RING4_5;
>   	adev->doorbell_index.uvd_vce.vce_ring6_7 = AMDGPU_VEGA20_DOORBELL64_VCE_RING6_7;
>   	adev->doorbell_index.max_assignment = 
> AMDGPU_VEGA20_DOORBELL_MAX_ASSIGNMENT << 1;
> +	adev->doorbell_index.sdma_doorbell_range = 20;
>   }
>   
> 
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