[PATCH 2/2] drm/amdgpu: stop masking the wptr all the time

[Khatri, Sunil]

On 10/8/2024 11:41 PM, Christian König wrote:
> Stop masking the wptr and decrementing the count_dw while writing into
> the ring buffer. We can do that all at once while pushing the changes to
> the HW.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c | 11 +++++------
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h |  4 ----
>   2 files changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> index a6e28fe3f8d6..364466d6d3de 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> @@ -90,12 +90,11 @@ int amdgpu_ring_alloc(struct amdgpu_ring *ring, unsigned int ndw)
>   	if (WARN_ON_ONCE(ndw > ring->max_dw))
>   		return -ENOMEM;
>   
> -	ring->count_dw = ndw;
> -	ring->wptr_old = ring->wptr;
> -
>   	if (ring->funcs->begin_use)
>   		ring->funcs->begin_use(ring);
>   
> +	ring->count_dw = ndw;
> +	ring->wptr_old = ring->wptr;
Does moving these after begin_use makes any difference? Otherwise looks 
good to me.

Reviewed-by: Sunil Khatri <sunil.khatri at amd.com> 
<mailto:sunil.khatri at amd.com>

Regards
Sunil Khatri


>   	return 0;
>   }
>   
> @@ -122,8 +121,6 @@ void amdgpu_ring_insert_nop(struct amdgpu_ring *ring, uint32_t count)
>   		memset32(ring->ring, ring->funcs->nop, chunk2);
>   
>   	ring->wptr += count;
> -	ring->wptr &= ring->ptr_mask;
> -	ring->count_dw -= count;
>   }
>   
>   /**
> @@ -153,9 +150,11 @@ void amdgpu_ring_commit(struct amdgpu_ring *ring)
>   {
>   	uint32_t count;
>   
> -	if (ring->count_dw < 0)
> +	if ((ring->wptr - ring->wptr_old) > ring->count_dw)
>   		DRM_ERROR("amdgpu: writing more dwords to the ring than expected!\n");
>   
> +	ring->wptr &= ring->ptr_mask;
> +
>   	/* We pad to match fetch size */
>   	count = ring->funcs->align_mask + 1 -
>   		(ring->wptr & ring->funcs->align_mask);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> index 36fc9578c53c..439793206b89 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
> @@ -378,8 +378,6 @@ static inline void amdgpu_ring_clear_ring(struct amdgpu_ring *ring)
>   static inline void amdgpu_ring_write(struct amdgpu_ring *ring, uint32_t v)
>   {
>   	ring->ring[ring->wptr++ & ring->buf_mask] = v;
> -	ring->wptr &= ring->ptr_mask;
> -	ring->count_dw--;
>   }
>   
>   static inline void amdgpu_ring_write_multiple(struct amdgpu_ring *ring,
> @@ -403,8 +401,6 @@ static inline void amdgpu_ring_write_multiple(struct amdgpu_ring *ring,
>   	}
>   
>   	ring->wptr += count_dw;
> -	ring->wptr &= ring->ptr_mask;
> -	ring->count_dw -= count_dw;
>   }
>   
>   /**
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