drm: dumb scanout create/mmap for intel/radeon (v3)

This is just an idea that might or might not be a good idea,
it basically adds two ioctls to create a dumb and map a dumb buffer
suitable for scanout. The handle can be passed to the KMS ioctls to create
a framebuffer.

It looks to me like it would be useful in the following cases:
a) in development drivers - we can always provide a shadowfb fallback.
b) libkms users - we can clean up libkms a lot and avoid linking
to libdrm_*.
c) plymouth via libkms is a lot easier.

Userspace bits would be just calls + mmaps. We could probably
mark these handles somehow as not being suitable for acceleartion
so as top stop people who are dumber than dumb.

Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 654faa803dc..4c95b5fd9df 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -2694,3 +2694,36 @@ void drm_mode_config_reset(struct drm_device *dev)
 			connector->funcs->reset(connector);
 }
 EXPORT_SYMBOL(drm_mode_config_reset);
+
+int drm_mode_create_dumb_ioctl(struct drm_device *dev,
+			       void *data, struct drm_file *file_priv)
+{
+	struct drm_mode_create_dumb *args = data;
+
+	if (!dev->driver->dumb_create)
+		return -ENOSYS;
+	return dev->driver->dumb_create(file_priv, dev, args);
+}
+
+int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
+			     void *data, struct drm_file *file_priv)
+{
+	struct drm_mode_map_dumb *args = data;
+
+	/* call driver ioctl to get mmap offset */
+	if (!dev->driver->dumb_map_offset)
+		return -ENOSYS;
+
+	return dev->driver->dumb_map_offset(file_priv, dev, args->handle, &args->offset);
+}
+
+int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
+				void *data, struct drm_file *file_priv)
+{
+	struct drm_mode_destroy_dumb *args = data;
+
+	if (!dev->driver->dumb_destroy)
+		return -ENOSYS;
+
+	return dev->driver->dumb_destroy(file_priv, dev, args->handle);
+}