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4f93624ee7
Put the callback docs into struct drm_driver, and the small overview into a DOC comment. Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/20161114115825.22050-7-daniel.vetter@ffwll.ch
128 lines
4.4 KiB
C
128 lines
4.4 KiB
C
/*
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* Copyright (c) 2006-2008 Intel Corporation
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* Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
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* Copyright (c) 2008 Red Hat Inc.
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* Copyright (c) 2016 Intel Corporation
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*
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* Permission to use, copy, modify, distribute, and sell this software and its
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* documentation for any purpose is hereby granted without fee, provided that
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* the above copyright notice appear in all copies and that both that copyright
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* notice and this permission notice appear in supporting documentation, and
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* that the name of the copyright holders not be used in advertising or
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* publicity pertaining to distribution of the software without specific,
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* written prior permission. The copyright holders make no representations
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* about the suitability of this software for any purpose. It is provided "as
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* is" without express or implied warranty.
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*
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* THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
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* EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
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* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
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* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
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* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
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* OF THIS SOFTWARE.
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*/
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#include <drm/drmP.h>
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#include "drm_crtc_internal.h"
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/**
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* DOC: overview
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*
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* The KMS API doesn't standardize backing storage object creation and leaves it
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* to driver-specific ioctls. Furthermore actually creating a buffer object even
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* for GEM-based drivers is done through a driver-specific ioctl - GEM only has
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* a common userspace interface for sharing and destroying objects. While not an
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* issue for full-fledged graphics stacks that include device-specific userspace
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* components (in libdrm for instance), this limit makes DRM-based early boot
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* graphics unnecessarily complex.
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*
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* Dumb objects partly alleviate the problem by providing a standard API to
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* create dumb buffers suitable for scanout, which can then be used to create
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* KMS frame buffers.
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*
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* To support dumb objects drivers must implement the dumb_create,
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* dumb_destroy and dumb_map_offset operations from struct &drm_driver. See
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* there for further details.
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*
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* Note that dumb objects may not be used for gpu acceleration, as has been
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* attempted on some ARM embedded platforms. Such drivers really must have
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* a hardware-specific ioctl to allocate suitable buffer objects.
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*/
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int drm_mode_create_dumb_ioctl(struct drm_device *dev,
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void *data, struct drm_file *file_priv)
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{
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struct drm_mode_create_dumb *args = data;
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u32 cpp, stride, size;
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if (!dev->driver->dumb_create)
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return -ENOSYS;
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if (!args->width || !args->height || !args->bpp)
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return -EINVAL;
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/* overflow checks for 32bit size calculations */
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/* NOTE: DIV_ROUND_UP() can overflow */
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cpp = DIV_ROUND_UP(args->bpp, 8);
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if (!cpp || cpp > 0xffffffffU / args->width)
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return -EINVAL;
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stride = cpp * args->width;
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if (args->height > 0xffffffffU / stride)
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return -EINVAL;
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/* test for wrap-around */
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size = args->height * stride;
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if (PAGE_ALIGN(size) == 0)
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return -EINVAL;
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/*
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* handle, pitch and size are output parameters. Zero them out to
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* prevent drivers from accidentally using uninitialized data. Since
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* not all existing userspace is clearing these fields properly we
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* cannot reject IOCTL with garbage in them.
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*/
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args->handle = 0;
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args->pitch = 0;
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args->size = 0;
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return dev->driver->dumb_create(file_priv, dev, args);
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}
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/**
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* drm_mode_mmap_dumb_ioctl - create an mmap offset for a dumb backing storage buffer
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* @dev: DRM device
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* @data: ioctl data
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* @file_priv: DRM file info
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*
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* Allocate an offset in the drm device node's address space to be able to
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* memory map a dumb buffer.
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*
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* Called by the user via ioctl.
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*
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* Returns:
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* Zero on success, negative errno on failure.
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*/
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int drm_mode_mmap_dumb_ioctl(struct drm_device *dev,
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void *data, struct drm_file *file_priv)
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{
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struct drm_mode_map_dumb *args = data;
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/* call driver ioctl to get mmap offset */
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if (!dev->driver->dumb_map_offset)
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return -ENOSYS;
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return dev->driver->dumb_map_offset(file_priv, dev, args->handle, &args->offset);
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}
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int drm_mode_destroy_dumb_ioctl(struct drm_device *dev,
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void *data, struct drm_file *file_priv)
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{
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struct drm_mode_destroy_dumb *args = data;
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if (!dev->driver->dumb_destroy)
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return -ENOSYS;
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return dev->driver->dumb_destroy(file_priv, dev, args->handle);
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}
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