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 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.
Signed-off-by: Simon Ser contact@emersion.fr Cc: Daniel Vetter daniel@ffwll.ch Cc: Pekka Paalanen ppaalanen@gmail.com --- include/uapi/drm/drm.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h index 3b810b53ba8b..9809078b0f51 100644 --- a/include/uapi/drm/drm.h +++ b/include/uapi/drm/drm.h @@ -1096,6 +1096,22 @@ 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 not DRM master and doesn't have &CAP_SYS_ADMIN, + * &drm_mode_fb_cmd2.handles will be zeroed. Planes are valid until one has a + * zero &drm_mode_fb_cmd2.pitches -- this can be used to compute the number of + * planes. + * + * If the framebuffer has a format modifier, &DRM_MODE_FB_MODIFIERS will be set + * in &drm_mode_fb_cmd2.flags. Otherwise, &drm_mode_fb_cmd2.modifier has + * undefined contents. + */ #define DRM_IOCTL_MODE_GETFB2 DRM_IOWR(0xCE, struct drm_mode_fb_cmd2)
/*