drm/fb-helper: Remove drm_fb_helper_defio_init() and update docs

 *

 * Drivers that support a dumb buffer with a virtual address and mmap support,

 * should try out the generic fbdev emulation using drm_fbdev_generic_setup().

 * It will automatically set up deferred I/O if the driver requires a shadow

 * buffer.

 *

 * Setup fbdev emulation by calling drm_fb_helper_fbdev_setup() and tear it

 * down by calling drm_fb_helper_fbdev_teardown().

 * For other drivers, setup fbdev emulation by calling

 * drm_fb_helper_fbdev_setup() and tear it down by calling

 * drm_fb_helper_fbdev_teardown().

 *

 * At runtime drivers should restore the fbdev console by using

 * drm_fb_helper_lastclose() as their &drm_driver.lastclose callback.

 * always run in process context since the fb_*() function could be running in

 * atomic context. If drm_fb_helper_deferred_io() is used as the deferred_io

 * callback it will also schedule dirty_work with the damage collected from the

 * mmap page writes. Drivers can use drm_fb_helper_defio_init() to setup

 * deferred I/O (coupled with drm_fb_helper_fbdev_teardown()).

 * mmap page writes.

 *

 * Deferred I/O is not compatible with SHMEM. Such drivers should request an

 * fbdev shadow buffer and call drm_fbdev_generic_setup() instead.

 */

static void drm_fb_helper_restore_lut_atomic(struct drm_crtc *crtc)

}

EXPORT_SYMBOL(drm_fb_helper_deferred_io);

/**

 * drm_fb_helper_defio_init - fbdev deferred I/O initialization

 * @fb_helper: driver-allocated fbdev helper

 *

 * This function allocates &fb_deferred_io, sets callback to

 * drm_fb_helper_deferred_io(), delay to 50ms and calls fb_deferred_io_init().

 * It should be called from the &drm_fb_helper_funcs->fb_probe callback.

 * drm_fb_helper_fbdev_teardown() cleans up deferred I/O.

 *

 * NOTE: A copy of &fb_ops is made and assigned to &info->fbops. This is done

 * because fb_deferred_io_cleanup() clears &fbops->fb_mmap and would thereby

 * affect other instances of that &fb_ops.

 *

 * Returns:

 * 0 on success or a negative error code on failure.

 */

int drm_fb_helper_defio_init(struct drm_fb_helper *fb_helper)

{

	struct fb_info *info = fb_helper->fbdev;

	struct fb_deferred_io *fbdefio;

	struct fb_ops *fbops;

	fbdefio = kzalloc(sizeof(*fbdefio), GFP_KERNEL);

	fbops = kzalloc(sizeof(*fbops), GFP_KERNEL);

	if (!fbdefio || !fbops) {

		kfree(fbdefio);

		kfree(fbops);

		return -ENOMEM;

	}

	info->fbdefio = fbdefio;

	fbdefio->delay = msecs_to_jiffies(50);

	fbdefio->deferred_io = drm_fb_helper_deferred_io;

	*fbops = *info->fbops;

	info->fbops = fbops;

	fb_deferred_io_init(info);

	return 0;

}

EXPORT_SYMBOL(drm_fb_helper_defio_init);

/**

 * drm_fb_helper_sys_read - wrapper around fb_sys_read

 * @info: fb_info struct pointer

 *

 * Drivers that set the dirty callback on their framebuffer will get a shadow

 * fbdev buffer that is blitted onto the real buffer. This is done in order to

 * make deferred I/O work with all kinds of buffers.

 * make deferred I/O work with all kinds of buffers. A shadow buffer can be

 * requested explicitly by setting struct drm_mode_config.prefer_shadow or

 * struct drm_mode_config.prefer_shadow_fbdev to true beforehand. This is

 * required to use generic fbdev emulation with SHMEM helpers.

 *

 * This function is safe to call even when there are no connectors present.

 * Setup will be retried on the next hotplug event.

void drm_fb_helper_deferred_io(struct fb_info *info,

			       struct list_head *pagelist);

int drm_fb_helper_defio_init(struct drm_fb_helper *fb_helper);

ssize_t drm_fb_helper_sys_read(struct fb_info *info, char __user *buf,

			       size_t count, loff_t *ppos);