[PATCH v2 2/2] drm: document DRM_IOCTL_PRIME_HANDLE_TO_FD and PRIME_FD_TO_HANDLE

[Pekka Paalanen]

On Fri, 17 Feb 2023 16:22:04 +0000
Simon Ser <contact at emersion.fr> wrote:

> v2: mention caps, note that the IOCTLs might fail, document that
> user-space needs a data structure to keep track of the
> handles (Daniel V.)
> 
> Signed-off-by: Simon Ser <contact at emersion.fr>
> Cc: Daniel Vetter <daniel at ffwll.ch>
> Cc: Pekka Paalanen <ppaalanen at gmail.com>
> Cc: Daniel Stone <daniel at fooishbar.org>
> ---
>  include/uapi/drm/drm.h | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> index 292e4778a2f4..a87bbbbca2d4 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -1025,7 +1025,37 @@ extern "C" {
>  #define DRM_IOCTL_UNLOCK		DRM_IOW( 0x2b, struct drm_lock)
>  #define DRM_IOCTL_FINISH		DRM_IOW( 0x2c, struct drm_lock)
>  
> +/**
> + * DRM_IOCTL_PRIME_HANDLE_TO_FD - Convert a GEM handle to a DMA-BUF FD.
> + *
> + * User-space sets &drm_prime_handle.handle with the GEM handle to export and
> + * &drm_prime_handle.flags, and gets back a DMA-BUF file descriptor in
> + * &drm_prime_handle.fd.
> + *
> + * The export can fail for any driver-specific reason, e.g. because export is
> + * not supported for this specific GEM handle (but might be for others).
> + *
> + * Support for exporting DMA-BUFs is advertised via &DRM_PRIME_CAP_EXPORT.
> + */
>  #define DRM_IOCTL_PRIME_HANDLE_TO_FD    DRM_IOWR(0x2d, struct drm_prime_handle)
> +/**
> + * DRM_IOCTL_PRIME_FD_TO_HANDLE - Convert a DMA-BUF FD to a GEM handle.
> + *
> + * User-space sets &drm_prime_handle.fd with a DMA-BUF file descriptor to
> + * import, and gets back a GEM handle in &drm_prime_handle.handle.
> + * &drm_prime_handle.flags is unused.
> + *
> + * If an existing GEM handle refers to the memory object backing the DMA-BUF,
> + * that GEM handle is returned. Therefore user-space which needs to handle
> + * arbitrary DMA-BUFs must have a user-space lookup data structure to manually
> + * reference-count duplicated GEM handles. For more information see
> + * &DRM_IOCTL_GEM_CLOSE.
> + *
> + * The import can fail for any driver-specific reason, e.g. because import is
> + * only supported for DMA-BUFs allocated on this DRM device.
> + *
> + * Support for importing DMA-BUFs is advertised via &DRM_PRIME_CAP_IMPORT.
> + */
>  #define DRM_IOCTL_PRIME_FD_TO_HANDLE    DRM_IOWR(0x2e, struct drm_prime_handle)
>  
>  #define DRM_IOCTL_AGP_ACQUIRE		DRM_IO(  0x30)

This patch too

Acked-by: Pekka Paalanen <pekka.paalanen at collabora.com>


Thanks,
pq
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