Re: [PATCH] drm/virtio: switch to generic fbdev emulation

From: Ezequiel Garcia
Date: Wed Jan 02 2019 - 12:06:40 EST


On Thu, 2018-12-13 at 14:49 +0100, Gerd Hoffmann wrote:

A few words explaining why the generic emulation is OK would be useful.

The commit might be clear for seasoned DRM developers, however
given this driver is a nice target for those learning DRM
(as it can be tested easily), I think having a more verbose
history is useful.

The patch looks good:

Reviewed-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>

> Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> ---
> drivers/gpu/drm/virtio/virtgpu_drv.h | 14 ---
> drivers/gpu/drm/virtio/virtgpu_display.c | 1 -
> drivers/gpu/drm/virtio/virtgpu_drv.c | 9 +-
> drivers/gpu/drm/virtio/virtgpu_fb.c | 191 -------------------------------
> drivers/gpu/drm/virtio/virtgpu_kms.c | 8 --
> 5 files changed, 8 insertions(+), 215 deletions(-)
>
> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
> index 1deb41d42e..63704915f8 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_drv.h
> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
> @@ -137,19 +137,10 @@ struct virtio_gpu_framebuffer {
> #define to_virtio_gpu_framebuffer(x) \
> container_of(x, struct virtio_gpu_framebuffer, base)
>
> -struct virtio_gpu_fbdev {
> - struct drm_fb_helper helper;
> - struct virtio_gpu_framebuffer vgfb;
> - struct virtio_gpu_device *vgdev;
> - struct delayed_work work;
> -};
> -
> struct virtio_gpu_mman {
> struct ttm_bo_device bdev;
> };
>
> -struct virtio_gpu_fbdev;
> -
> struct virtio_gpu_queue {
> struct virtqueue *vq;
> spinlock_t qlock;
> @@ -180,8 +171,6 @@ struct virtio_gpu_device {
>
> struct virtio_gpu_mman mman;
>
> - /* pointer to fbdev info structure */
> - struct virtio_gpu_fbdev *vgfbdev;
> struct virtio_gpu_output outputs[VIRTIO_GPU_MAX_SCANOUTS];
> uint32_t num_scanouts;
>
> @@ -249,9 +238,6 @@ int virtio_gpu_mode_dumb_mmap(struct drm_file *file_priv,
> uint32_t handle, uint64_t *offset_p);
>
> /* virtio_fb */
> -#define VIRTIO_GPUFB_CONN_LIMIT 1
> -int virtio_gpu_fbdev_init(struct virtio_gpu_device *vgdev);
> -void virtio_gpu_fbdev_fini(struct virtio_gpu_device *vgdev);
> int virtio_gpu_surface_dirty(struct virtio_gpu_framebuffer *qfb,
> struct drm_clip_rect *clips,
> unsigned int num_clips);
> diff --git a/drivers/gpu/drm/virtio/virtgpu_display.c b/drivers/gpu/drm/virtio/virtgpu_display.c
> index b5580b11a0..e1c223e18d 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_display.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_display.c
> @@ -390,6 +390,5 @@ void virtio_gpu_modeset_fini(struct virtio_gpu_device *vgdev)
>
> for (i = 0 ; i < vgdev->num_scanouts; ++i)
> kfree(vgdev->outputs[i].edid);
> - virtio_gpu_fbdev_fini(vgdev);
> drm_mode_config_cleanup(vgdev->ddev);
> }
> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c b/drivers/gpu/drm/virtio/virtgpu_drv.c
> index f7f32a885a..7df50920c1 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_drv.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
> @@ -42,13 +42,20 @@ module_param_named(modeset, virtio_gpu_modeset, int, 0400);
>
> static int virtio_gpu_probe(struct virtio_device *vdev)
> {
> + int ret;
> +
> if (vgacon_text_force() && virtio_gpu_modeset == -1)
> return -EINVAL;
>
> if (virtio_gpu_modeset == 0)
> return -EINVAL;
>
> - return drm_virtio_init(&driver, vdev);
> + ret = drm_virtio_init(&driver, vdev);
> + if (ret)
> + return ret;
> +
> + drm_fbdev_generic_setup(vdev->priv, 32);
> + return 0;
> }
>
> static void virtio_gpu_remove(struct virtio_device *vdev)
> diff --git a/drivers/gpu/drm/virtio/virtgpu_fb.c b/drivers/gpu/drm/virtio/virtgpu_fb.c
> index fb1cc8b2f1..b07584b1c2 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_fb.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_fb.c
> @@ -27,8 +27,6 @@
> #include <drm/drm_fb_helper.h>
> #include "virtgpu_drv.h"
>
> -#define VIRTIO_GPU_FBCON_POLL_PERIOD (HZ / 60)
> -
> static int virtio_gpu_dirty_update(struct virtio_gpu_framebuffer *fb,
> bool store, int x, int y,
> int width, int height)
> @@ -150,192 +148,3 @@ int virtio_gpu_surface_dirty(struct virtio_gpu_framebuffer *vgfb,
> 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_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 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_FORMAT_HOST_XRGB8888;
> -
> - 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_cmd_create_resource(vgdev, obj, format,
> - mode_cmd.width, mode_cmd.height);
> -
> - ret = virtio_gpu_object_kmap(obj);
> - if (ret) {
> - DRM_ERROR("failed to kmap fb %d\n", ret);
> - goto err_obj_vmap;
> - }
> -
> - /* attach the object to the resource */
> - ret = virtio_gpu_object_attach(vgdev, obj, 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_object_detach(vgdev, obj);
> -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->base.obj[0])
> - vgfb->base.obj[0] = 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;
> -}
> diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c
> index 3af6181c05..1072064a0d 100644
> --- a/drivers/gpu/drm/virtio/virtgpu_kms.c
> +++ b/drivers/gpu/drm/virtio/virtgpu_kms.c
> @@ -28,11 +28,6 @@
> #include <drm/drmP.h>
> #include "virtgpu_drv.h"
>
> -static int virtio_gpu_fbdev = 1;
> -
> -MODULE_PARM_DESC(fbdev, "Disable/Enable framebuffer device & console");
> -module_param_named(fbdev, virtio_gpu_fbdev, int, 0400);
> -
> static void virtio_gpu_config_changed_work_func(struct work_struct *work)
> {
> struct virtio_gpu_device *vgdev =
> @@ -212,9 +207,6 @@ int virtio_gpu_driver_load(struct drm_device *dev, unsigned long flags)
> virtio_gpu_cmd_get_display_info(vgdev);
> wait_event_timeout(vgdev->resp_wq, !vgdev->display_info_pending,
> 5 * HZ);
> - if (virtio_gpu_fbdev)
> - virtio_gpu_fbdev_init(vgdev);
> -
> return 0;
>
> err_modeset: