Re: [PATCH 1/4] drm/amdgpu: Fix allocating extra dwords for rings

["Christian König" <christian.koenig@amd.com>]

On 01.09.25 12:00, Timur Kristóf wrote:
> The amdgpu_bo_create_kernel function takes a byte count,
> so we need to multiply the extra dword count by four.
> (The ring_size is already in bytes so that one is correct here.)

Good catch, it just doesn't make a difference in practice since everything is rounded up to 4k anyway.

But I'm really wondering if we shouldn't replace the extra_dw with extra_bytes instead.

It should only be used by some multimedia engines anyway.

Regards,
Christian.

> 
> Fixes: c8c1a1d2ef04 ("drm/amdgpu: define and add extra dword for jpeg ring")
> Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> index 6379bb25bf5c..13f0f0209cbe 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
> @@ -364,11 +364,12 @@ int amdgpu_ring_init(struct amdgpu_device *adev, struct amdgpu_ring *ring,
>  
>  	/* Allocate ring buffer */
>  	if (ring->ring_obj == NULL) {
> -		r = amdgpu_bo_create_kernel(adev, ring->ring_size + ring->funcs->extra_dw, PAGE_SIZE,
> -					    AMDGPU_GEM_DOMAIN_GTT,
> -					    &ring->ring_obj,
> -					    &ring->gpu_addr,
> -					    (void **)&ring->ring);
> +		r = amdgpu_bo_create_kernel(adev, ring->ring_size + ring->funcs->extra_dw * 4,
> +						PAGE_SIZE,
> +						AMDGPU_GEM_DOMAIN_GTT,
> +						&ring->ring_obj,
> +						&ring->gpu_addr,
> +						(void **)&ring->ring);
>  		if (r) {
>  			dev_err(adev->dev, "(%d) ring create failed\n", r);
>  			kvfree(ring->ring_backup);