diff options
| author | Simon Ser <contact@emersion.fr> | 2023-02-17 16:22:04 +0000 |
|---|---|---|
| committer | Simon Ser <contact@emersion.fr> | 2023-02-20 10:42:00 +0100 |
| commit | 6068771673a38efc31ed5b99645176b4d3a33129 (patch) | |
| tree | 48004c7b7faed850965c1b46789815609be7ffbd /include/uapi/drm/drm.h | |
| parent | 61a55f8b1ebcde68bc7bfd57435b1b3bb1121b8f (diff) | |
| download | lwn-6068771673a38efc31ed5b99645176b4d3a33129.tar.gz lwn-6068771673a38efc31ed5b99645176b4d3a33129.zip | |
drm: document DRM_IOCTL_PRIME_HANDLE_TO_FD and PRIME_FD_TO_HANDLE
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@emersion.fr>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Pekka Paalanen <ppaalanen@gmail.com>
Cc: Daniel Stone <daniel@fooishbar.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230217162151.59996-2-contact@emersion.fr
Diffstat (limited to 'include/uapi/drm/drm.h')
| -rw-r--r-- | include/uapi/drm/drm.h | 30 |
1 files changed, 30 insertions, 0 deletions
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) |