vgem_device
vgem_device = devm_drm_dev_alloc(&fdev->dev, &vgem_driver,
struct vgem_device, drm);
if (IS_ERR(vgem_device)) {
ret = PTR_ERR(vgem_device);
vgem_device->faux_dev = fdev;
ret = drm_dev_register(&vgem_device->drm, 0);
struct faux_device *fdev = vgem_device->faux_dev;
drm_dev_unregister(&vgem_device->drm);
} *vgem_device;