Commit d208d875 authored by Simon Ser's avatar Simon Ser
Browse files

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: default avatarSimon Ser <contact@emersion.fr>
Reviewed-by: default avatarDaniel Stone <daniels@collabora.com>
Acked-by: default avatarPekka Paalanen <pekka.paalanen@collabora.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Dennis Filder <d.filder@web.de>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231020101926.145327-2-contact@emersion.fr
parent 0226ba39

drivers/gpu/drm/drm_crtc_internal.h

+2 −0
Original line number Diff line number Diff line
@@ -222,6 +222,8 @@ int drm_mode_addfb2_ioctl(struct drm_device *dev, 
			  void *data, struct drm_file *file_priv);

int drm_mode_rmfb_ioctl(struct drm_device *dev,

			void *data, struct drm_file *file_priv);

int drm_mode_closefb_ioctl(struct drm_device *dev,

			   void *data, struct drm_file *file_priv);

int drm_mode_getfb(struct drm_device *dev,

		   void *data, struct drm_file *file_priv);

int drm_mode_getfb2_ioctl(struct drm_device *dev,

drivers/gpu/drm/drm_framebuffer.c

+22 −0
Original line number Diff line number Diff line
@@ -480,6 +480,28 @@ int drm_mode_rmfb_ioctl(struct drm_device *dev, 
	return drm_mode_rmfb(dev, *fb_id, file_priv);

}



int drm_mode_closefb_ioctl(struct drm_device *dev,

			   void *data, struct drm_file *file_priv)

{

	struct drm_mode_closefb *r = data;

	struct drm_framebuffer *fb;

	int ret;



	if (!drm_core_check_feature(dev, DRIVER_MODESET))

		return -EOPNOTSUPP;



	if (r->pad)

		return -EINVAL;



	fb = drm_framebuffer_lookup(dev, file_priv, r->fb_id);

	if (!fb)

		return -ENOENT;



	ret = drm_mode_closefb(fb, file_priv);

	drm_framebuffer_put(fb);

	return ret;

}



/**

 * drm_mode_getfb - get FB info

 * @dev: drm device for the ioctl

drivers/gpu/drm/drm_ioctl.c

+1 −0
Original line number Diff line number Diff line
@@ -675,6 +675,7 @@ static const struct drm_ioctl_desc drm_ioctls[] = { 
	DRM_IOCTL_DEF(DRM_IOCTL_MODE_ADDFB, drm_mode_addfb_ioctl, 0),

	DRM_IOCTL_DEF(DRM_IOCTL_MODE_ADDFB2, drm_mode_addfb2_ioctl, 0),

	DRM_IOCTL_DEF(DRM_IOCTL_MODE_RMFB, drm_mode_rmfb_ioctl, 0),

	DRM_IOCTL_DEF(DRM_IOCTL_MODE_CLOSEFB, drm_mode_closefb_ioctl, 0),

	DRM_IOCTL_DEF(DRM_IOCTL_MODE_PAGE_FLIP, drm_mode_page_flip_ioctl, DRM_MASTER),

	DRM_IOCTL_DEF(DRM_IOCTL_MODE_DIRTYFB, drm_mode_dirtyfb_ioctl, DRM_MASTER),

	DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATE_DUMB, drm_mode_create_dumb_ioctl, 0),

include/uapi/drm/drm.h

+20 −0
Original line number Diff line number Diff line
@@ -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.

include/uapi/drm/drm_mode.h

+10 −0
Original line number Diff line number Diff line
@@ -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