From d208d875667e2a29beeec5d475f4b6b164b632fa Mon Sep 17 00:00:00 2001 From: Simon Ser Date: Fri, 20 Oct 2023 10:19:45 +0000 Subject: drm: introduce CLOSEFB IOCTL This new IOCTL allows callers to close a framebuffer without disabling planes or CRTCs. This takes inspiration from Rob Clark's unref_fb IOCTL [1] and DRM_MODE_FB_PERSIST [2]. User-space patch for wlroots available at [3]. IGT test available at [4]. v2: add an extra pad field just in case we want to extend this IOCTL in the future (Pekka, Sima). [1]: https://lore.kernel.org/dri-devel/20170509153654.23464-1-robdclark@gmail.com/ [2]: https://lore.kernel.org/dri-devel/20211006151921.312714-1-contact@emersion.fr/ [3]: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/4394 [4]: https://lists.freedesktop.org/archives/igt-dev/2023-October/063294.html Signed-off-by: Simon Ser Reviewed-by: Daniel Stone Acked-by: Pekka Paalanen Cc: Hans de Goede Cc: Dennis Filder Cc: Daniel Vetter Cc: Rob Clark Cc: Sean Paul Link: https://patchwork.freedesktop.org/patch/msgid/20231020101926.145327-2-contact@emersion.fr --- include/uapi/drm/drm.h | 20 ++++++++++++++++++++ include/uapi/drm/drm_mode.h | 10 ++++++++++ 2 files changed, 30 insertions(+) (limited to 'include') diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h index de723566c5ae..8662b5aeea0c 100644 --- a/include/uapi/drm/drm.h +++ b/include/uapi/drm/drm.h @@ -1218,6 +1218,26 @@ extern "C" { #define DRM_IOCTL_SYNCOBJ_EVENTFD DRM_IOWR(0xCF, struct drm_syncobj_eventfd) +/** + * DRM_IOCTL_MODE_CLOSEFB - Close a framebuffer. + * + * This closes a framebuffer previously added via ADDFB/ADDFB2. The IOCTL + * argument is a framebuffer object ID. + * + * This IOCTL is similar to &DRM_IOCTL_MODE_RMFB, except it doesn't disable + * planes and CRTCs. As long as the framebuffer is used by a plane, it's kept + * alive. When the plane no longer uses the framebuffer (because the + * framebuffer is replaced with another one, or the plane is disabled), the + * framebuffer is cleaned up. + * + * This is useful to implement flicker-free transitions between two processes. + * + * Depending on the threat model, user-space may want to ensure that the + * framebuffer doesn't expose any sensitive user information: closed + * framebuffers attached to a plane can be read back by the next DRM master. + */ +#define DRM_IOCTL_MODE_CLOSEFB DRM_IOWR(0xD0, struct drm_mode_closefb) + /* * Device specific ioctls should only be in their respective headers * The device specific ioctl range is from 0x40 to 0x9f. diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h index 128d09138ceb..09e7a471ee30 100644 --- a/include/uapi/drm/drm_mode.h +++ b/include/uapi/drm/drm_mode.h @@ -1323,6 +1323,16 @@ struct drm_mode_rect { __s32 y2; }; +/** + * struct drm_mode_closefb + * @fb_id: Framebuffer ID. + * @pad: Must be zero. + */ +struct drm_mode_closefb { + __u32 fb_id; + __u32 pad; +}; + #if defined(__cplusplus) } #endif -- cgit v1.2.3