drivers/gpu/drm/virtio/virtgpu_fb.c - third_party/linux - Git at Google

 /*
  * Copyright (C) 2015 Red Hat, Inc.
  * All Rights Reserved.
  *
  * 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 COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS 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.
  */

 #include <drm/drmP.h>
 #include <drm/drm_fb_helper.h>
 #include "virtgpu_drv.h"

 #define VIRTIO_GPU_FBCON_POLL_PERIOD (HZ / 60)

 struct virtio_gpu_fbdev {
 	struct drm_fb_helper           helper;
 	struct virtio_gpu_framebuffer  vgfb;
 	struct virtio_gpu_device       *vgdev;
 	struct delayed_work            work;
 };

 static int virtio_gpu_dirty_update(struct virtio_gpu_framebuffer *fb,
 				   bool store, int x, int y,
 				   int width, int height)
 {
 	struct drm_device *dev = fb->base.dev;
 	struct virtio_gpu_device *vgdev = dev->dev_private;
 	bool store_for_later = false;
 	int bpp = fb->base.format->cpp[0];
 	int x2, y2;
 	unsigned long flags;
 	struct virtio_gpu_object *obj = gem_to_virtio_gpu_obj(fb->obj);

 	if ((width <= 0) ||
 	    (x + width > fb->base.width) ||
 	    (y + height > fb->base.height)) {
 		DRM_DEBUG("values out of range %dx%d+%d+%d, fb %dx%d\n",
 			  width, height, x, y,
 			  fb->base.width, fb->base.height);
 		return -EINVAL;
 	}

 	/*
 	 * Can be called with pretty much any context (console output
 	 * path).  If we are in atomic just store the dirty rect info
 	 * to send out the update later.
 	 *
 	 * Can't test inside spin lock.
 	 */
 	if (in_atomic() || store)
 		store_for_later = true;

 	x2 = x + width - 1;
 	y2 = y + height - 1;

 	spin_lock_irqsave(&fb->dirty_lock, flags);

 	if (fb->y1 < y)
 		y = fb->y1;
 	if (fb->y2 > y2)
 		y2 = fb->y2;
 	if (fb->x1 < x)
 		x = fb->x1;
 	if (fb->x2 > x2)
 		x2 = fb->x2;

 	if (store_for_later) {
 		fb->x1 = x;
 		fb->x2 = x2;
 		fb->y1 = y;
 		fb->y2 = y2;
 		spin_unlock_irqrestore(&fb->dirty_lock, flags);
 		return 0;
 	}

 	fb->x1 = fb->y1 = INT_MAX;
 	fb->x2 = fb->y2 = 0;

 	spin_unlock_irqrestore(&fb->dirty_lock, flags);

 	{
 		uint32_t offset;
 		uint32_t w = x2 - x + 1;
 		uint32_t h = y2 - y + 1;

 		offset = (y * fb->base.pitches[0]) + x * bpp;

 		virtio_gpu_cmd_transfer_to_host_2d(vgdev, obj->hw_res_handle,
 						   offset,
 						   cpu_to_le32(w),
 						   cpu_to_le32(h),
 						   cpu_to_le32(x),
 						   cpu_to_le32(y),
 						   NULL);

 	}
 	virtio_gpu_cmd_resource_flush(vgdev, obj->hw_res_handle,
 				      x, y, x2 - x + 1, y2 - y + 1);
 	return 0;
 }

 int virtio_gpu_surface_dirty(struct virtio_gpu_framebuffer *vgfb,
 			     struct drm_clip_rect *clips,
 			     unsigned int num_clips)
 {
 	struct virtio_gpu_device *vgdev = vgfb->base.dev->dev_private;
 	struct virtio_gpu_object *obj = gem_to_virtio_gpu_obj(vgfb->obj);
 	struct drm_clip_rect norect;
 	struct drm_clip_rect *clips_ptr;
 	int left, right, top, bottom;
 	int i;
 	int inc = 1;

 	if (!num_clips) {
 		num_clips = 1;
 		clips = &norect;
 		norect.x1 = norect.y1 = 0;
 		norect.x2 = vgfb->base.width;
 		norect.y2 = vgfb->base.height;
 	}
 	left = clips->x1;
 	right = clips->x2;
 	top = clips->y1;
 	bottom = clips->y2;

 	/* skip the first clip rect */
 	for (i = 1, clips_ptr = clips + inc;
 	     i < num_clips; i++, clips_ptr += inc) {
 		left = min_t(int, left, (int)clips_ptr->x1);
 		right = max_t(int, right, (int)clips_ptr->x2);
 		top = min_t(int, top, (int)clips_ptr->y1);
 		bottom = max_t(int, bottom, (int)clips_ptr->y2);
 	}

 	if (obj->dumb)
 		return virtio_gpu_dirty_update(vgfb, false, left, top,
 					       right - left, bottom - top);

 	virtio_gpu_cmd_resource_flush(vgdev, obj->hw_res_handle,
 				      left, top, right - left, bottom - top);
 	return 0;
 }

 static void virtio_gpu_fb_dirty_work(struct work_struct *work)
 {
 	struct delayed_work *delayed_work = to_delayed_work(work);
 	struct virtio_gpu_fbdev *vfbdev =
 		container_of(delayed_work, struct virtio_gpu_fbdev, work);
 	struct virtio_gpu_framebuffer *vgfb = &vfbdev->vgfb;

 	virtio_gpu_dirty_update(&vfbdev->vgfb, false, vgfb->x1, vgfb->y1,
 				vgfb->x2 - vgfb->x1, vgfb->y2 - vgfb->y1);
 }

 static void virtio_gpu_3d_fillrect(struct fb_info *info,
 				   const struct fb_fillrect *rect)
 {
 	struct virtio_gpu_fbdev *vfbdev = info->par;

 	drm_fb_helper_sys_fillrect(info, rect);
 	virtio_gpu_dirty_update(&vfbdev->vgfb, true, rect->dx, rect->dy,
 			     rect->width, rect->height);
 	schedule_delayed_work(&vfbdev->work, VIRTIO_GPU_FBCON_POLL_PERIOD);
 }

 static void virtio_gpu_3d_copyarea(struct fb_info *info,
 				   const struct fb_copyarea *area)
 {
 	struct virtio_gpu_fbdev *vfbdev = info->par;

 	drm_fb_helper_sys_copyarea(info, area);
 	virtio_gpu_dirty_update(&vfbdev->vgfb, true, area->dx, area->dy,
 			   area->width, area->height);
 	schedule_delayed_work(&vfbdev->work, VIRTIO_GPU_FBCON_POLL_PERIOD);
 }

 static void virtio_gpu_3d_imageblit(struct fb_info *info,
 				    const struct fb_image *image)
 {
 	struct virtio_gpu_fbdev *vfbdev = info->par;

 	drm_fb_helper_sys_imageblit(info, image);
 	virtio_gpu_dirty_update(&vfbdev->vgfb, true, image->dx, image->dy,
 			     image->width, image->height);
 	schedule_delayed_work(&vfbdev->work, VIRTIO_GPU_FBCON_POLL_PERIOD);
 }

 static struct fb_ops virtio_gpufb_ops = {
 	.owner = THIS_MODULE,
 	DRM_FB_HELPER_DEFAULT_OPS,
 	.fb_fillrect = virtio_gpu_3d_fillrect,
 	.fb_copyarea = virtio_gpu_3d_copyarea,
 	.fb_imageblit = virtio_gpu_3d_imageblit,
 };

 static int virtio_gpu_vmap_fb(struct virtio_gpu_device *vgdev,
 			      struct virtio_gpu_object *obj)
 {
 	return virtio_gpu_object_kmap(obj, NULL);
 }

 static int virtio_gpufb_create(struct drm_fb_helper *helper,
 			       struct drm_fb_helper_surface_size *sizes)
 {
 	struct virtio_gpu_fbdev *vfbdev =
 		container_of(helper, struct virtio_gpu_fbdev, helper);
 	struct drm_device *dev = helper->dev;
 	struct virtio_gpu_device *vgdev = dev->dev_private;
 	struct fb_info *info;
 	struct drm_framebuffer *fb;
 	struct drm_mode_fb_cmd2 mode_cmd = {};
 	struct virtio_gpu_object *obj;
 	uint32_t resid, format, size;
 	int ret;

 	mode_cmd.width = sizes->surface_width;
 	mode_cmd.height = sizes->surface_height;
 	mode_cmd.pitches[0] = mode_cmd.width * 4;
 	mode_cmd.pixel_format = drm_mode_legacy_fb_format(32, 24);

 	format = virtio_gpu_translate_format(mode_cmd.pixel_format);
 	if (format == 0)
 		return -EINVAL;

 	size = mode_cmd.pitches[0] * mode_cmd.height;
 	obj = virtio_gpu_alloc_object(dev, size, false, true);
 	if (IS_ERR(obj))
 		return PTR_ERR(obj);

 	virtio_gpu_resource_id_get(vgdev, &resid);
 	virtio_gpu_cmd_create_resource(vgdev, resid, format,
 				       mode_cmd.width, mode_cmd.height);

 	ret = virtio_gpu_vmap_fb(vgdev, obj);
 	if (ret) {
 		DRM_ERROR("failed to vmap fb %d\n", ret);
 		goto err_obj_vmap;
 	}

 	/* attach the object to the resource */
 	ret = virtio_gpu_object_attach(vgdev, obj, resid, NULL);
 	if (ret)
 		goto err_obj_attach;

 	info = drm_fb_helper_alloc_fbi(helper);
 	if (IS_ERR(info)) {
 		ret = PTR_ERR(info);
 		goto err_fb_alloc;
 	}

 	info->par = helper;

 	ret = virtio_gpu_framebuffer_init(dev, &vfbdev->vgfb,
 					  &mode_cmd, &obj->gem_base);
 	if (ret)
 		goto err_fb_alloc;

 	fb = &vfbdev->vgfb.base;

 	vfbdev->helper.fb = fb;

 	strcpy(info->fix.id, "virtiodrmfb");
 	info->fbops = &virtio_gpufb_ops;
 	info->pixmap.flags = FB_PIXMAP_SYSTEM;

 	info->screen_buffer = obj->vmap;
 	info->screen_size = obj->gem_base.size;
 	drm_fb_helper_fill_fix(info, fb->pitches[0], fb->format->depth);
 	drm_fb_helper_fill_var(info, &vfbdev->helper,
 			       sizes->fb_width, sizes->fb_height);

 	info->fix.mmio_start = 0;
 	info->fix.mmio_len = 0;
 	return 0;

 err_fb_alloc:
 	virtio_gpu_cmd_resource_inval_backing(vgdev, resid);
 err_obj_attach:
 err_obj_vmap:
 	virtio_gpu_gem_free_object(&obj->gem_base);
 	return ret;
 }

 static int virtio_gpu_fbdev_destroy(struct drm_device *dev,
 				    struct virtio_gpu_fbdev *vgfbdev)
 {
 	struct virtio_gpu_framebuffer *vgfb = &vgfbdev->vgfb;

 	drm_fb_helper_unregister_fbi(&vgfbdev->helper);

 	if (vgfb->obj)
 		vgfb->obj = NULL;
 	drm_fb_helper_fini(&vgfbdev->helper);
 	drm_framebuffer_cleanup(&vgfb->base);

 	return 0;
 }
 static const struct drm_fb_helper_funcs virtio_gpu_fb_helper_funcs = {
 	.fb_probe = virtio_gpufb_create,
 };

 int virtio_gpu_fbdev_init(struct virtio_gpu_device *vgdev)
 {
 	struct virtio_gpu_fbdev *vgfbdev;
 	int bpp_sel = 32; /* TODO: parameter from somewhere? */
 	int ret;

 	vgfbdev = kzalloc(sizeof(struct virtio_gpu_fbdev), GFP_KERNEL);
 	if (!vgfbdev)
 		return -ENOMEM;

 	vgfbdev->vgdev = vgdev;
 	vgdev->vgfbdev = vgfbdev;
 	INIT_DELAYED_WORK(&vgfbdev->work, virtio_gpu_fb_dirty_work);

 	drm_fb_helper_prepare(vgdev->ddev, &vgfbdev->helper,
 			      &virtio_gpu_fb_helper_funcs);
 	ret = drm_fb_helper_init(vgdev->ddev, &vgfbdev->helper,
 				 VIRTIO_GPUFB_CONN_LIMIT);
 	if (ret) {
 		kfree(vgfbdev);
 		return ret;
 	}

 	drm_fb_helper_single_add_all_connectors(&vgfbdev->helper);
 	drm_fb_helper_initial_config(&vgfbdev->helper, bpp_sel);
 	return 0;
 }

 void virtio_gpu_fbdev_fini(struct virtio_gpu_device *vgdev)
 {
 	if (!vgdev->vgfbdev)
 		return;

 	virtio_gpu_fbdev_destroy(vgdev->ddev, vgdev->vgfbdev);
 	kfree(vgdev->vgfbdev);
 	vgdev->vgfbdev = NULL;
 }
	/*
	* Copyright (C) 2015 Red Hat, Inc.
	* All Rights Reserved.
	*
	* 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 COPYRIGHT OWNER(S) AND/OR ITS SUPPLIERS 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.
	*/

	#include <drm/drmP.h>
	#include <drm/drm_fb_helper.h>
	#include "virtgpu_drv.h"

	#define VIRTIO_GPU_FBCON_POLL_PERIOD (HZ / 60)

	struct virtio_gpu_fbdev {
	struct drm_fb_helper helper;
	struct virtio_gpu_framebuffer vgfb;
	struct virtio_gpu_device *vgdev;
	struct delayed_work work;
	};

	static int virtio_gpu_dirty_update(struct virtio_gpu_framebuffer *fb,
	bool store, int x, int y,
	int width, int height)
	{
	struct drm_device *dev = fb->base.dev;
	struct virtio_gpu_device *vgdev = dev->dev_private;
	bool store_for_later = false;
	int bpp = fb->base.format->cpp[0];
	int x2, y2;
	unsigned long flags;
	struct virtio_gpu_object *obj = gem_to_virtio_gpu_obj(fb->obj);

	if ((width <= 0) \|\|
	(x + width > fb->base.width) \|\|
	(y + height > fb->base.height)) {
	DRM_DEBUG("values out of range %dx%d+%d+%d, fb %dx%d\n",
	width, height, x, y,
	fb->base.width, fb->base.height);
	return -EINVAL;
	}

	/*
	* Can be called with pretty much any context (console output
	* path). If we are in atomic just store the dirty rect info
	* to send out the update later.
	*
	* Can't test inside spin lock.
	*/
	if (in_atomic() \|\| store)
	store_for_later = true;

	x2 = x + width - 1;
	y2 = y + height - 1;

	spin_lock_irqsave(&fb->dirty_lock, flags);

	if (fb->y1 < y)
	y = fb->y1;
	if (fb->y2 > y2)
	y2 = fb->y2;
	if (fb->x1 < x)
	x = fb->x1;
	if (fb->x2 > x2)
	x2 = fb->x2;

	if (store_for_later) {
	fb->x1 = x;
	fb->x2 = x2;
	fb->y1 = y;
	fb->y2 = y2;
	spin_unlock_irqrestore(&fb->dirty_lock, flags);
	return 0;
	}

	fb->x1 = fb->y1 = INT_MAX;
	fb->x2 = fb->y2 = 0;

	spin_unlock_irqrestore(&fb->dirty_lock, flags);

	{
	uint32_t offset;
	uint32_t w = x2 - x + 1;
	uint32_t h = y2 - y + 1;

	offset = (y * fb->base.pitches[0]) + x * bpp;

	virtio_gpu_cmd_transfer_to_host_2d(vgdev, obj->hw_res_handle,
	offset,
	cpu_to_le32(w),
	cpu_to_le32(h),
	cpu_to_le32(x),
	cpu_to_le32(y),
	NULL);

	}
	virtio_gpu_cmd_resource_flush(vgdev, obj->hw_res_handle,
	x, y, x2 - x + 1, y2 - y + 1);
	return 0;
	}

	int virtio_gpu_surface_dirty(struct virtio_gpu_framebuffer *vgfb,
	struct drm_clip_rect *clips,
	unsigned int num_clips)
	{
	struct virtio_gpu_device *vgdev = vgfb->base.dev->dev_private;
	struct virtio_gpu_object *obj = gem_to_virtio_gpu_obj(vgfb->obj);
	struct drm_clip_rect norect;
	struct drm_clip_rect *clips_ptr;
	int left, right, top, bottom;
	int i;
	int inc = 1;

	if (!num_clips) {
	num_clips = 1;
	clips = &norect;
	norect.x1 = norect.y1 = 0;
	norect.x2 = vgfb->base.width;
	norect.y2 = vgfb->base.height;
	}
	left = clips->x1;
	right = clips->x2;
	top = clips->y1;
	bottom = clips->y2;

	/* skip the first clip rect */
	for (i = 1, clips_ptr = clips + inc;
	i < num_clips; i++, clips_ptr += inc) {
	left = min_t(int, left, (int)clips_ptr->x1);
	right = max_t(int, right, (int)clips_ptr->x2);
	top = min_t(int, top, (int)clips_ptr->y1);
	bottom = max_t(int, bottom, (int)clips_ptr->y2);
	}

	if (obj->dumb)
	return virtio_gpu_dirty_update(vgfb, false, left, top,
	right - left, bottom - top);

	virtio_gpu_cmd_resource_flush(vgdev, obj->hw_res_handle,
	left, top, right - left, bottom - top);
	return 0;
	}

	static void virtio_gpu_fb_dirty_work(struct work_struct *work)
	{
	struct delayed_work *delayed_work = to_delayed_work(work);
	struct virtio_gpu_fbdev *vfbdev =
	container_of(delayed_work, struct virtio_gpu_fbdev, work);
	struct virtio_gpu_framebuffer *vgfb = &vfbdev->vgfb;

	virtio_gpu_dirty_update(&vfbdev->vgfb, false, vgfb->x1, vgfb->y1,
	vgfb->x2 - vgfb->x1, vgfb->y2 - vgfb->y1);
	}

	static void virtio_gpu_3d_fillrect(struct fb_info *info,
	const struct fb_fillrect *rect)
	{
	struct virtio_gpu_fbdev *vfbdev = info->par;

	drm_fb_helper_sys_fillrect(info, rect);
	virtio_gpu_dirty_update(&vfbdev->vgfb, true, rect->dx, rect->dy,
	rect->width, rect->height);
	schedule_delayed_work(&vfbdev->work, VIRTIO_GPU_FBCON_POLL_PERIOD);
	}

	static void virtio_gpu_3d_copyarea(struct fb_info *info,
	const struct fb_copyarea *area)
	{
	struct virtio_gpu_fbdev *vfbdev = info->par;

	drm_fb_helper_sys_copyarea(info, area);
	virtio_gpu_dirty_update(&vfbdev->vgfb, true, area->dx, area->dy,
	area->width, area->height);
	schedule_delayed_work(&vfbdev->work, VIRTIO_GPU_FBCON_POLL_PERIOD);
	}

	static void virtio_gpu_3d_imageblit(struct fb_info *info,
	const struct fb_image *image)
	{
	struct virtio_gpu_fbdev *vfbdev = info->par;

	drm_fb_helper_sys_imageblit(info, image);
	virtio_gpu_dirty_update(&vfbdev->vgfb, true, image->dx, image->dy,
	image->width, image->height);
	schedule_delayed_work(&vfbdev->work, VIRTIO_GPU_FBCON_POLL_PERIOD);
	}

	static struct fb_ops virtio_gpufb_ops = {
	.owner = THIS_MODULE,
	DRM_FB_HELPER_DEFAULT_OPS,
	.fb_fillrect = virtio_gpu_3d_fillrect,
	.fb_copyarea = virtio_gpu_3d_copyarea,
	.fb_imageblit = virtio_gpu_3d_imageblit,
	};

	static int virtio_gpu_vmap_fb(struct virtio_gpu_device *vgdev,
	struct virtio_gpu_object *obj)
	{
	return virtio_gpu_object_kmap(obj, NULL);
	}

	static int virtio_gpufb_create(struct drm_fb_helper *helper,
	struct drm_fb_helper_surface_size *sizes)
	{
	struct virtio_gpu_fbdev *vfbdev =
	container_of(helper, struct virtio_gpu_fbdev, helper);
	struct drm_device *dev = helper->dev;
	struct virtio_gpu_device *vgdev = dev->dev_private;
	struct fb_info *info;
	struct drm_framebuffer *fb;
	struct drm_mode_fb_cmd2 mode_cmd = {};
	struct virtio_gpu_object *obj;
	uint32_t resid, format, size;
	int ret;

	mode_cmd.width = sizes->surface_width;
	mode_cmd.height = sizes->surface_height;
	mode_cmd.pitches[0] = mode_cmd.width * 4;
	mode_cmd.pixel_format = drm_mode_legacy_fb_format(32, 24);

	format = virtio_gpu_translate_format(mode_cmd.pixel_format);
	if (format == 0)
	return -EINVAL;

	size = mode_cmd.pitches[0] * mode_cmd.height;
	obj = virtio_gpu_alloc_object(dev, size, false, true);
	if (IS_ERR(obj))
	return PTR_ERR(obj);

	virtio_gpu_resource_id_get(vgdev, &resid);
	virtio_gpu_cmd_create_resource(vgdev, resid, format,
	mode_cmd.width, mode_cmd.height);

	ret = virtio_gpu_vmap_fb(vgdev, obj);
	if (ret) {
	DRM_ERROR("failed to vmap fb %d\n", ret);
	goto err_obj_vmap;
	}

	/* attach the object to the resource */
	ret = virtio_gpu_object_attach(vgdev, obj, resid, NULL);
	if (ret)
	goto err_obj_attach;

	info = drm_fb_helper_alloc_fbi(helper);
	if (IS_ERR(info)) {
	ret = PTR_ERR(info);
	goto err_fb_alloc;
	}

	info->par = helper;

	ret = virtio_gpu_framebuffer_init(dev, &vfbdev->vgfb,
	&mode_cmd, &obj->gem_base);
	if (ret)
	goto err_fb_alloc;

	fb = &vfbdev->vgfb.base;

	vfbdev->helper.fb = fb;

	strcpy(info->fix.id, "virtiodrmfb");
	info->fbops = &virtio_gpufb_ops;
	info->pixmap.flags = FB_PIXMAP_SYSTEM;

	info->screen_buffer = obj->vmap;
	info->screen_size = obj->gem_base.size;
	drm_fb_helper_fill_fix(info, fb->pitches[0], fb->format->depth);
	drm_fb_helper_fill_var(info, &vfbdev->helper,
	sizes->fb_width, sizes->fb_height);

	info->fix.mmio_start = 0;
	info->fix.mmio_len = 0;
	return 0;

	err_fb_alloc:
	virtio_gpu_cmd_resource_inval_backing(vgdev, resid);
	err_obj_attach:
	err_obj_vmap:
	virtio_gpu_gem_free_object(&obj->gem_base);
	return ret;
	}

	static int virtio_gpu_fbdev_destroy(struct drm_device *dev,
	struct virtio_gpu_fbdev *vgfbdev)
	{
	struct virtio_gpu_framebuffer *vgfb = &vgfbdev->vgfb;

	drm_fb_helper_unregister_fbi(&vgfbdev->helper);

	if (vgfb->obj)
	vgfb->obj = NULL;
	drm_fb_helper_fini(&vgfbdev->helper);
	drm_framebuffer_cleanup(&vgfb->base);

	return 0;
	}
	static const struct drm_fb_helper_funcs virtio_gpu_fb_helper_funcs = {
	.fb_probe = virtio_gpufb_create,
	};

	int virtio_gpu_fbdev_init(struct virtio_gpu_device *vgdev)
	{
	struct virtio_gpu_fbdev *vgfbdev;
	int bpp_sel = 32; /* TODO: parameter from somewhere? */
	int ret;

	vgfbdev = kzalloc(sizeof(struct virtio_gpu_fbdev), GFP_KERNEL);
	if (!vgfbdev)
	return -ENOMEM;

	vgfbdev->vgdev = vgdev;
	vgdev->vgfbdev = vgfbdev;
	INIT_DELAYED_WORK(&vgfbdev->work, virtio_gpu_fb_dirty_work);

	drm_fb_helper_prepare(vgdev->ddev, &vgfbdev->helper,
	&virtio_gpu_fb_helper_funcs);
	ret = drm_fb_helper_init(vgdev->ddev, &vgfbdev->helper,
	VIRTIO_GPUFB_CONN_LIMIT);
	if (ret) {
	kfree(vgfbdev);
	return ret;
	}

	drm_fb_helper_single_add_all_connectors(&vgfbdev->helper);
	drm_fb_helper_initial_config(&vgfbdev->helper, bpp_sel);
	return 0;
	}

	void virtio_gpu_fbdev_fini(struct virtio_gpu_device *vgdev)
	{
	if (!vgdev->vgfbdev)
	return;

	virtio_gpu_fbdev_destroy(vgdev->ddev, vgdev->vgfbdev);
	kfree(vgdev->vgfbdev);
	vgdev->vgfbdev = NULL;
	}