From 4f93624ee7c05d5a8da77934a8a9e0e64e121ae6 Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Mon, 14 Nov 2016 12:58:21 +0100 Subject: drm: Consolidate dumb buffer docs Put the callback docs into struct drm_driver, and the small overview into a DOC comment. Reviewed-by: Chris Wilson Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/20161114115825.22050-7-daniel.vetter@ffwll.ch --- Documentation/gpu/drm-kms.rst | 42 ++---------------------------------------- 1 file changed, 2 insertions(+), 40 deletions(-) (limited to 'Documentation/gpu/drm-kms.rst') diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst index cb0d3537b705..4edfb6d91250 100644 --- a/Documentation/gpu/drm-kms.rst +++ b/Documentation/gpu/drm-kms.rst @@ -72,46 +72,8 @@ DRM Format Handling Dumb Buffer Objects =================== -The KMS API doesn't standardize backing storage object creation and -leaves it to driver-specific ioctls. Furthermore actually creating a -buffer object even for GEM-based drivers is done through a -driver-specific ioctl - GEM only has a common userspace interface for -sharing and destroying objects. While not an issue for full-fledged -graphics stacks that include device-specific userspace components (in -libdrm for instance), this limit makes DRM-based early boot graphics -unnecessarily complex. - -Dumb objects partly alleviate the problem by providing a standard API to -create dumb buffers suitable for scanout, which can then be used to -create KMS frame buffers. - -To support dumb objects drivers must implement the dumb_create, -dumb_destroy and dumb_map_offset operations. - -- int (\*dumb_create)(struct drm_file \*file_priv, struct - drm_device \*dev, struct drm_mode_create_dumb \*args); - The dumb_create operation creates a driver object (GEM or TTM - handle) suitable for scanout based on the width, height and depth - from the struct :c:type:`struct drm_mode_create_dumb - ` argument. It fills the argument's - handle, pitch and size fields with a handle for the newly created - object and its line pitch and size in bytes. - -- int (\*dumb_destroy)(struct drm_file \*file_priv, struct - drm_device \*dev, uint32_t handle); - The dumb_destroy operation destroys a dumb object created by - dumb_create. - -- int (\*dumb_map_offset)(struct drm_file \*file_priv, struct - drm_device \*dev, uint32_t handle, uint64_t \*offset); - The dumb_map_offset operation associates an mmap fake offset with - the object given by the handle and returns it. Drivers must use the - :c:func:`drm_gem_create_mmap_offset()` function to associate - the fake offset as described in ?. - -Note that dumb objects may not be used for gpu acceleration, as has been -attempted on some ARM embedded platforms. Such drivers really must have -a hardware-specific ioctl to allocate suitable buffer objects. +.. kernel-doc:: drivers/gpu/drm/drm_dumb_buffers.c + :doc: overview Plane Abstraction ================= -- cgit