[PATCH] drm/virtio: Allow userspace to mmap() framebuffer

[Joshua Watt]

Reports the size of the virtgpu framebuffer to userspace and installs
the deferred I/O handlers so that userspace can mmap() and write to it.

Signed-off-by: Joshua Watt <JPEWhacker at gmail.com>
---
 drivers/gpu/drm/virtio/virtgpu_fb.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/virtio/virtgpu_fb.c b/drivers/gpu/drm/virtio/virtgpu_fb.c
index fb1cc8b2f119..9f44c8d27c64 100644
--- a/drivers/gpu/drm/virtio/virtgpu_fb.c
+++ b/drivers/gpu/drm/virtio/virtgpu_fb.c
@@ -266,11 +266,15 @@ static int virtio_gpufb_create(struct drm_fb_helper *helper,
 	info->fbops = &virtio_gpufb_ops;
 	info->pixmap.flags = FB_PIXMAP_SYSTEM;
 
+	info->fix.smem_start = 0;
+	info->fix.smem_len = size;
+
 	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);
+	drm_fb_helper_defio_init(helper);
 
 	info->fix.mmio_start = 0;
 	info->fix.mmio_len = 0;
-- 
2.20.1