Re: [PATCH 1/1] drm/amdkfd: Fix unaligned doorbell absolute offset for gfx8

[Felix Kuehling <felix.kuehling@amd.com>]

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[+Mukul]

On 2023-09-27 12:16, Arvind Yadav wrote:
> This patch is to adjust the absolute doorbell offset
> against the doorbell id considering the doorbell
> size of 32/64 bit.
>
> Cc: Christian Koenig<christian.koenig@amd.com>
> Cc: Alex Deucher<alexander.deucher@amd.com>
> Signed-off-by: Shashank Sharma<shashank.sharma@amd.com>
> Signed-off-by: Arvind Yadav<Arvind.Yadav@amd.com>
> ---
>   drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c | 11 ++++++++++-
>   1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> index 0d3d538b64eb..c327f7f604d7 100644
> --- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> +++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
> @@ -407,7 +407,16 @@ static int allocate_doorbell(struct qcm_process_device *qpd,
>   
>   	q->properties.doorbell_off = amdgpu_doorbell_index_on_bar(dev->adev,
>   								  qpd->proc_doorbells,
> -								  q->doorbell_id);
> +								  0);

Looks like we're now always calling amdgpu_doorbell_index_on_bar with 
the third parameter = 0. So we could remove that parameter. It doesn't 
do us any good and only causes bugs if we use any non-0 value.


> +
> +	/* Adjust the absolute doorbell offset against the doorbell id considering
> +	 * the doorbell size of 32/64 bit.
> +	 */
> +	if (!KFD_IS_SOC15(dev))
> +		q->properties.doorbell_off += q->doorbell_id;
> +	else
> +		q->properties.doorbell_off += q->doorbell_id * 2;

This could be simplified and generalized as

	q->properties.doorbell_off += q->doorbell_id * dev->kfd->device_info.doorbell_size / 4;

Regards,
   Felix


> +
>   	return 0;
>   }
>   

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