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drm: document DRM_IOCTL_PRIME_HANDLE_TO_FD and PRIME_FD_TO_HANDLE

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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 <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Pekka Paalanen <[email protected]>
Cc: Daniel Stone <[email protected]>
Reviewed-by: Daniel Vetter <[email protected]>
Acked-by: Pekka Paalanen <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
This commit is contained in:
Simon Ser committed 2023-02-20 10:42:00 +01:00
1 parent 61a55f8b1e
commit 6068771673
1 file changed
+30
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include/uapi/drm/drm.h
+30
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@@ -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)