Re: [PATCH v5 11/16] drm/panfrost: Provide a custom dma_buf implementation

[Steven Price <steven.price@arm.com>]

On 30/10/2025 14:05, Boris Brezillon wrote:
> Before we introduce cached CPU mappings, we want a dma_buf
> implementation satisfying synchronization requests around CPU
> accesses coming from a dma_buf exported by our driver. Let's
> provide our own implementation relying on the default
> gem_shmem_prime helpers designed for that purpose.
> 
> v5:
> - New patch
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>

Reviewed-by: Steven Price <steven.price@arm.com>

> ---
>  drivers/gpu/drm/panfrost/panfrost_drv.c |  1 +
>  drivers/gpu/drm/panfrost/panfrost_gem.c | 19 +++++++++++++++++++
>  drivers/gpu/drm/panfrost/panfrost_gem.h |  2 ++
>  3 files changed, 22 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
> index 1c3c574cd64a..e3cdc0c95a56 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> @@ -852,6 +852,7 @@ static const struct drm_driver panfrost_drm_driver = {
>  
>  	.gem_create_object	= panfrost_gem_create_object,
>  	.gem_prime_import_sg_table = panfrost_gem_prime_import_sg_table,
> +	.gem_prime_get_dma_buf_ops = panfrost_gem_prime_get_dma_buf_ops,
>  #ifdef CONFIG_DEBUG_FS
>  	.debugfs_init = panfrost_debugfs_init,
>  #endif
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.c b/drivers/gpu/drm/panfrost/panfrost_gem.c
> index 0528de674a4f..070ea7108af6 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.c
> @@ -323,6 +323,25 @@ panfrost_gem_create(struct drm_device *dev, size_t size, u32 flags)
>  	return bo;
>  }
>  
> +static const struct dma_buf_ops panfrost_dma_buf_ops = {
> +	.attach = drm_gem_map_attach,
> +	.detach = drm_gem_map_detach,
> +	.map_dma_buf = drm_gem_shmem_prime_map_dma_buf,
> +	.unmap_dma_buf = drm_gem_shmem_prime_unmap_dma_buf,
> +	.release = drm_gem_dmabuf_release,
> +	.mmap = drm_gem_dmabuf_mmap,
> +	.vmap = drm_gem_dmabuf_vmap,
> +	.vunmap = drm_gem_dmabuf_vunmap,
> +	.begin_cpu_access = drm_gem_shmem_prime_begin_cpu_access,
> +	.end_cpu_access = drm_gem_shmem_prime_end_cpu_access,
> +};
> +
> +const struct dma_buf_ops *
> +panfrost_gem_prime_get_dma_buf_ops(struct drm_device *dev)
> +{
> +	return &panfrost_dma_buf_ops;
> +}
> +
>  struct drm_gem_object *
>  panfrost_gem_prime_import_sg_table(struct drm_device *dev,
>  				   struct dma_buf_attachment *attach,
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h
> index 8de3e76f2717..c63264464271 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.h
> @@ -130,6 +130,8 @@ struct drm_gem_object *
>  panfrost_gem_prime_import_sg_table(struct drm_device *dev,
>  				   struct dma_buf_attachment *attach,
>  				   struct sg_table *sgt);
> +const struct dma_buf_ops *
> +panfrost_gem_prime_get_dma_buf_ops(struct drm_device *dev);
>  
>  struct panfrost_gem_object *
>  panfrost_gem_create(struct drm_device *dev, size_t size, u32 flags);