diff options
| author | Simon Ser <contact@emersion.fr> | 2021-11-23 11:24:04 +0000 |
|---|---|---|
| committer | Simon Ser <contact@emersion.fr> | 2021-12-14 12:03:32 +0100 |
| commit | 43d5ac7d07023cd133b978de473b3400edad941f (patch) | |
| tree | 9545b5ee45e22de74af27bfa97776b1844a870a4 /include/uapi/drm/drm.h | |
| parent | 1c66496b1391699040d0ddda21fe1979865f6eba (diff) | |
drm: document DRM_IOCTL_MODE_GETFB2
There are a few details specific to the GETFB2 IOCTL.
It's not immediately clear how user-space should check for the
number of planes. Suggest using the handles field or the pitches
field.
The modifier array is filled with zeroes, ie. DRM_FORMAT_MOD_LINEAR.
So explicitly tell user-space to not look at it unless the flag is
set.
Changes in v2 (Daniel):
- Mention that handles should be used to compute the number of planes,
and only refer to pitches as a fallback.
- Reword bit about undefined modifier.
Signed-off-by: Simon Ser <contact@emersion.fr>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Acked-by: Daniel Stone <daniels@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211123112400.22245-1-contact@emersion.fr
Diffstat (limited to 'include/uapi/drm/drm.h')
| -rw-r--r-- | include/uapi/drm/drm.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h index 3b810b53ba8b..642808520d92 100644 --- a/include/uapi/drm/drm.h +++ b/include/uapi/drm/drm.h @@ -1096,6 +1096,24 @@ extern "C" { #define DRM_IOCTL_SYNCOBJ_TRANSFER DRM_IOWR(0xCC, struct drm_syncobj_transfer) #define DRM_IOCTL_SYNCOBJ_TIMELINE_SIGNAL DRM_IOWR(0xCD, struct drm_syncobj_timeline_array) +/** + * DRM_IOCTL_MODE_GETFB2 - Get framebuffer metadata. + * + * This queries metadata about a framebuffer. User-space fills + * &drm_mode_fb_cmd2.fb_id as the input, and the kernels fills the rest of the + * struct as the output. + * + * If the client is DRM master or has &CAP_SYS_ADMIN, &drm_mode_fb_cmd2.handles + * will be filled with GEM buffer handles. Planes are valid until one has a + * zero handle -- this can be used to compute the number of planes. + * + * Otherwise, &drm_mode_fb_cmd2.handles will be zeroed and planes are valid + * until one has a zero &drm_mode_fb_cmd2.pitches. + * + * If the framebuffer has a format modifier, &DRM_MODE_FB_MODIFIERS will be set + * in &drm_mode_fb_cmd2.flags and &drm_mode_fb_cmd2.modifier will contain the + * modifier. Otherwise, user-space must ignore &drm_mode_fb_cmd2.modifier. + */ #define DRM_IOCTL_MODE_GETFB2 DRM_IOWR(0xCE, struct drm_mode_fb_cmd2) /* |