linux/drivers/gpu/drm/drm_dumb_buffers.c

/*
 * Copyright (c) 2006-2008 Intel Corporation
 * Copyright (c) 2007 Dave Airlie <[email protected]>
 * Copyright (c) 2008 Red Hat Inc.
 * Copyright (c) 2016 Intel Corporation
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 */

#include <drm/drm_device.h>
#include <drm/drm_drv.h>
#include <drm/drm_gem.h>
#include <drm/drm_mode.h>

#include "drm_crtc_internal.h"
#include "drm_internal.h"

/**
 * DOC: overview
 *
 * 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 &drm_driver.dumb_create
 * and &drm_driver.dumb_map_offset operations (the latter defaults to
 * drm_gem_dumb_map_offset() if not set). Drivers that don't use GEM handles
 * additionally need to implement the &drm_driver.dumb_destroy operation. See
 * the callbacks for further details.
 *
 * 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.
 */

int drm_mode_create_dumb(struct drm_device *dev,
			 struct drm_mode_create_dumb *args,
			 struct drm_file *file_priv)
{ … }

int drm_mode_create_dumb_ioctl(struct drm_device *dev,
			       void *data, struct drm_file *file_priv)
{ … }

/**
 * drm_mode_mmap_dumb_ioctl - create an mmap offset for a dumb backing storage buffer
 * @dev: DRM device
 * @data: ioctl data
 * @file_priv: DRM file info
 *
 * Allocate an offset in the drm device node's address space to be able to
 * memory map a dumb buffer.
 *
 * Called by the user via ioctl.
 *
 * Returns:
 * Zero on success, negative errno on failure.
 */
int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
			     void *data, struct drm_file *file_priv)
{ … }

int drm_mode_destroy_dumb(struct drm_device *dev, u32 handle,
			  struct drm_file *file_priv)
{ … }

int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
				void *data, struct drm_file *file_priv)
{ … }