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c11e391da2
The userspace might need some sort of cache coherency management e.g. when CPU
and GPU domains are being accessed through dma-buf at the same time. To
circumvent this problem there are begin/end coherency markers, that forward
directly to existing dma-buf device drivers vfunc hooks. Userspace can make use
of those markers through the DMA_BUF_IOCTL_SYNC ioctl. The sequence would be
used like following:
- mmap dma-buf fd
- for each drawing/upload cycle in CPU 1. SYNC_START ioctl, 2. read/write
to mmap area 3. SYNC_END ioctl. This can be repeated as often as you
want (with the new data being consumed by the GPU or say scanout device)
- munmap once you don't need the buffer any more
v2 (Tiago): Fix header file type names (u64 -> __u64)
v3 (Tiago): Add documentation. Use enum dma_buf_sync_flags to the begin/end
dma-buf functions. Check for overflows in start/length.
v4 (Tiago): use 2d regions for sync.
v5 (Tiago): forget about 2d regions (v4); use _IOW in DMA_BUF_IOCTL_SYNC and
remove range information from struct dma_buf_sync.
v6 (Tiago): use __u64 structured padded flags instead enum. Adjust
documentation about the recommendation on using sync ioctls.
v7 (Tiago): Alex' nit on flags definition and being even more wording in the
doc about sync usage.
v9 (Tiago): remove useless is_dma_buf_file check. Fix sync.flags conditionals
and its mask order check. Add <linux/types.h> include in dma-buf.h.
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: David Herrmann <dh.herrmann@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1455228291-29640-1-git-send-email-tiago.vignatti@intel.com
41 lines
1.3 KiB
C
41 lines
1.3 KiB
C
/*
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* Framework for buffer objects that can be shared across devices/subsystems.
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*
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* Copyright(C) 2015 Intel Ltd
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef _DMA_BUF_UAPI_H_
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#define _DMA_BUF_UAPI_H_
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#include <linux/types.h>
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/* begin/end dma-buf functions used for userspace mmap. */
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struct dma_buf_sync {
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__u64 flags;
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};
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#define DMA_BUF_SYNC_READ (1 << 0)
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#define DMA_BUF_SYNC_WRITE (2 << 0)
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#define DMA_BUF_SYNC_RW (DMA_BUF_SYNC_READ | DMA_BUF_SYNC_WRITE)
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#define DMA_BUF_SYNC_START (0 << 2)
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#define DMA_BUF_SYNC_END (1 << 2)
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#define DMA_BUF_SYNC_VALID_FLAGS_MASK \
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(DMA_BUF_SYNC_RW | DMA_BUF_SYNC_END)
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#define DMA_BUF_BASE 'b'
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#define DMA_BUF_IOCTL_SYNC _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync)
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#endif
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