libweston: remove fbdev backend

Fbdev backend was deprecated in the Weston 10.0.0 release with
6338dbd581. Before that, I suggested
already in 2019 to remove it, but it was too soon then. Now it seems the
final voices asking for fbdev to be kept have been satisfied, see the
linked issue.

Fbdev-backend uses a kernel graphics UAPI (fbdev) which is sub-par for a
Wayland compositor: you cannot do GPU accelerated graphics in any
reasonable way, no hotplug support, multi-output support is tedious, and
so on. Most importantly, Linux has deprecated fbdev a long time ago due
to the UAPI fitting modern systems and use cases very poorly, but cannot
get rid of it if any users remain. Let's do here what we can to reduce
fbdev usage.

I am doing color management related additions to libweston which require
adding checks to every backend. One backend less is less churn to write
and review.

Libweston major version has already been bumped to 11, so the next
release will be Weston 11, without fbdev. enum weston_compositor_backend
entries change their numerical values.

Fixes: https://gitlab.freedesktop.org/wayland/weston/-/issues/581

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>

include/libweston/backend-fbdev.h

@@ -1,69 +0,0 @@
-/*
- * Copyright © 2016 Benoit Gschwind
- *
- * Permission is hereby granted, free of charge, to any person obtaining
- * a copy of this software and associated documentation files (the
- * "Software"), to deal in the Software without restriction, including
- * without limitation the rights to use, copy, modify, merge, publish,
- * distribute, sublicense, and/or sell copies of the Software, and to
- * permit persons to whom the Software is furnished to do so, subject to
- * the following conditions:
- *
- * The above copyright notice and this permission notice (including the
- * next paragraph) shall be included in all copies or substantial
- * portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
- * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
- * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
- * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
- * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
- * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
- * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
- * SOFTWARE.
- */
-
-#ifndef WESTON_COMPOSITOR_FBDEV_H
-#define WESTON_COMPOSITOR_FBDEV_H
-
-#ifdef  __cplusplus
-extern "C" {
-#endif
-
-#include <stdint.h>
-
-#include <libweston/libweston.h>
-
-#define WESTON_FBDEV_BACKEND_CONFIG_VERSION 3
-
-struct libinput_device;
-
-struct weston_fbdev_backend_config {
-	struct weston_backend_config base;
-
-	char *device;
-
-	/** Callback used to configure input devices.
-	 *
-	 * This function will be called by the backend when a new input device
-	 * needs to be configured.
-	 * If NULL the device will use the default configuration.
-	 */
-	void (*configure_device)(struct weston_compositor *compositor,
-				 struct libinput_device *device);
-
-	/** The seat to be used for input and output.
-	 *
-	 * If seat_id is NULL, the seat is taken from XDG_SEAT environment
-	 * variable. If neither is set, "seat0" is used. The backend will
-	 * take ownership of the seat_id pointer and will free it on
-	 * backend destruction.
-	 */
-	char *seat_id;
-};
-
-#ifdef  __cplusplus
-}
-#endif
-
-#endif /* WESTON_COMPOSITOR_FBDEV_H */

include/libweston/libweston.h

@@ -1842,7 +1842,6 @@ weston_compositor_add_destroy_listener_once(struct weston_compositor *compositor
 
 enum weston_compositor_backend {
 	WESTON_BACKEND_DRM,
-	WESTON_BACKEND_FBDEV,
 	WESTON_BACKEND_HEADLESS,
 	WESTON_BACKEND_RDP,
 	WESTON_BACKEND_WAYLAND,

include/libweston/meson.build

@@ -12,7 +12,6 @@ install_headers(
 )
 
 backend_drm_h =      files('backend-drm.h')
-backend_fbdev_h =    files('backend-fbdev.h')
 backend_headless_h = files('backend-headless.h')
 backend_rdp_h =      files('backend-rdp.h')
 backend_wayland_h =  files('backend-wayland.h')