From c11e391da2a8fe973c3c2398452000bed505851e Mon Sep 17 00:00:00 2001 From: Daniel Vetter Date: Thu, 11 Feb 2016 20:04:51 -0200 Subject: dma-buf: Add ioctls to allow userspace to flush MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 include in dma-buf.h. Cc: Ville Syrjälä Cc: David Herrmann Cc: Sumit Semwal Reviewed-by: Stéphane Marchesin Signed-off-by: Daniel Vetter Signed-off-by: Tiago Vignatti Reviewed-by: David Herrmann Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1455228291-29640-1-git-send-email-tiago.vignatti@intel.com --- include/uapi/linux/dma-buf.h | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 include/uapi/linux/dma-buf.h (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/dma-buf.h b/include/uapi/linux/dma-buf.h new file mode 100644 index 000000000000..fb0dedb7c121 --- /dev/null +++ b/include/uapi/linux/dma-buf.h @@ -0,0 +1,40 @@ +/* + * Framework for buffer objects that can be shared across devices/subsystems. + * + * Copyright(C) 2015 Intel Ltd + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for + * more details. + * + * You should have received a copy of the GNU General Public License along with + * this program. If not, see . + */ + +#ifndef _DMA_BUF_UAPI_H_ +#define _DMA_BUF_UAPI_H_ + +#include + +/* begin/end dma-buf functions used for userspace mmap. */ +struct dma_buf_sync { + __u64 flags; +}; + +#define DMA_BUF_SYNC_READ (1 << 0) +#define DMA_BUF_SYNC_WRITE (2 << 0) +#define DMA_BUF_SYNC_RW (DMA_BUF_SYNC_READ | DMA_BUF_SYNC_WRITE) +#define DMA_BUF_SYNC_START (0 << 2) +#define DMA_BUF_SYNC_END (1 << 2) +#define DMA_BUF_SYNC_VALID_FLAGS_MASK \ + (DMA_BUF_SYNC_RW | DMA_BUF_SYNC_END) + +#define DMA_BUF_BASE 'b' +#define DMA_BUF_IOCTL_SYNC _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync) + +#endif -- cgit v1.2.3