[PATCH] drm: Improve dumb callback docs

[Daniel Vetter]

Noticed while reviewing a patch from Eric. Also add a todo for the
dumb_map_offset callbacks (it should be simple to do, but piles of
work). Plus fix up vbox, because vbox.

Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Cc: Maxime Ripard <maxime.ripard at bootlin.com>
Cc: Sean Paul <sean at poorly.run>
Cc: David Airlie <airlied at linux.ie>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Cc: Hans de Goede <hdegoede at redhat.com>
Cc: Nicholas Mc Guire <der.herr at hofr.at>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Fabio Rafael da Rosa <fdr at pid42.net>
---
 Documentation/gpu/todo.rst           | 10 ++++++++++
 drivers/staging/vboxvideo/vbox_drv.c |  1 -
 include/drm/drm_drv.h                |  9 +++++++--
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
index 31ef4adc91c9..8c2df0ed37d9 100644
--- a/Documentation/gpu/todo.rst
+++ b/Documentation/gpu/todo.rst
@@ -28,6 +28,16 @@ them, but also all the virtual ones used by KVM, so everyone qualifies).
 
 Contact: Daniel Vetter, Thierry Reding, respective driver maintainers
 
+Remove custom dumb_map_offset implementations
+---------------------------------------------
+
+All GEM based drivers should be using drm_gem_create_mmap_offset() instead.
+Audit each individual driver, make sure it'll work with the generic
+implementation (there's lots of outdated locking leftovers in various
+implementations), and then remove it.
+
+Contact: Daniel Vetter, respective driver maintainers
+
 Switch from reference/unreference to get/put
 --------------------------------------------
 
diff --git a/drivers/staging/vboxvideo/vbox_drv.c b/drivers/staging/vboxvideo/vbox_drv.c
index 257030460fb6..d3e23dd70c1b 100644
--- a/drivers/staging/vboxvideo/vbox_drv.c
+++ b/drivers/staging/vboxvideo/vbox_drv.c
@@ -279,7 +279,6 @@ static struct drm_driver driver = {
 	.gem_free_object_unlocked = vbox_gem_free_object,
 	.dumb_create = vbox_dumb_create,
 	.dumb_map_offset = vbox_dumb_mmap_offset,
-	.dumb_destroy = drm_gem_dumb_destroy,
 	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
 	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
 	.gem_prime_export = drm_gem_prime_export,
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index dbb2f6ad184a..c3d6d53555d3 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -527,8 +527,10 @@ struct drm_driver {
 	 * @dumb_map_offset:
 	 *
 	 * Allocate an offset in the drm device node's address space to be able to
-	 * memory map a dumb buffer. GEM-based drivers must use
-	 * drm_gem_create_mmap_offset() to implement this.
+	 * memory map a dumb buffer.
+	 *
+	 * The default implementation is drm_gem_create_mmap_offset(). GEM based
+	 * drivers must not overwrite this.
 	 *
 	 * Called by the user via ioctl.
 	 *
@@ -548,6 +550,9 @@ struct drm_driver {
 	 *
 	 * Called by the user via ioctl.
 	 *
+	 * The default implementation is drm_gem_dumb_destroy(). GEM based drivers
+	 * must not overwrite this.
+	 *
 	 * Returns:
 	 *
 	 * Zero on success, negative errno on failure.
-- 
2.19.1