libcamera/libcamera.git - libcamera official repository

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Diffstat (limited to 'src/cam/capture.cpp')

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/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ /* * 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 <http://www.gnu.org/licenses/>. */ #ifndef _DMA_BUF_UAPI_H_ #define _DMA_BUF_UAPI_H_ #include <linux/types.h> /** * struct dma_buf_sync - Synchronize with CPU access. * * When a DMA buffer is accessed from the CPU via mmap, it is not always * possible to guarantee coherency between the CPU-visible map and underlying * memory. To manage coherency, DMA_BUF_IOCTL_SYNC must be used to bracket * any CPU access to give the kernel the chance to shuffle memory around if * needed. * * Prior to accessing the map, the client must call DMA_BUF_IOCTL_SYNC * with DMA_BUF_SYNC_START and the appropriate read/write flags. Once the * access is complete, the client should call DMA_BUF_IOCTL_SYNC with * DMA_BUF_SYNC_END and the same read/write flags. * * The synchronization provided via DMA_BUF_IOCTL_SYNC only provides cache * coherency. It does not prevent other processes or devices from * accessing the memory at the same time. If synchronization with a GPU or * other device driver is required, it is the client's responsibility to * wait for buffer to be ready for reading or writing before calling this * ioctl with DMA_BUF_SYNC_START. Likewise, the client must ensure that * follow-up work is not submitted to GPU or other device driver until * after this ioctl has been called with DMA_BUF_SYNC_END? * * If the driver or API with which the client is interacting uses implicit * synchronization, waiting for prior work to complete can be done via * poll() on the DMA buffer file descriptor. If the driver or API requires * explicit synchronization, the client may have to wait on a sync_file or * other synchronization primitive outside the scope of the DMA buffer API. */ struct dma_buf_sync { /** * @flags: Set of access flags * * DMA_BUF_SYNC_START: * Indicates the start of a map access session. * * DMA_BUF_SYNC_END: * Indicates the end of a map access session. * * DMA_BUF_SYNC_READ: * Indicates that the mapped DMA buffer will be read by the * client via the CPU map. * * DMA_BUF_SYNC_WRITE: * Indicates that the mapped DMA buffer will be written by the * client via the CPU map. * * DMA_BUF_SYNC_RW: * An alias for DMA_BUF_SYNC_READ | DMA_BUF_SYNC_WRITE. */ __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_NAME_LEN 32 /** * struct dma_buf_export_sync_file - Get a sync_file from a dma-buf * * Userspace can perform a DMA_BUF_IOCTL_EXPORT_SYNC_FILE to retrieve the * current set of fences on a dma-buf file descriptor as a sync_file. CPU * waits via poll() or other driver-specific mechanisms typically wait on * whatever fences are on the dma-buf at the time the wait begins. This * is similar except that it takes a snapshot of the current fences on the * dma-buf for waiting later instead of waiting immediately. This is * useful for modern graphics APIs such as Vulkan which assume an explicit * synchronization model but still need to inter-operate with dma-buf. * * The intended usage pattern is the following: * * 1. Export a sync_file with flags corresponding to the expected GPU usage * via DMA_BUF_IOCTL_EXPORT_SYNC_FILE. * * 2. Submit rendering work which uses the dma-buf. The work should wait on * the exported sync file before rendering and produce another sync_file * when complete. * * 3. Import the rendering-complete sync_file into the dma-buf with flags * corresponding to the GPU usage via DMA_BUF_IOCTL_IMPORT_SYNC_FILE. * * Unlike doing implicit synchronization via a GPU kernel driver's exec ioctl, * the above is not a single atomic operation. If userspace wants to ensure * ordering via these fences, it is the respnosibility of userspace to use * locks or other mechanisms to ensure that no other context adds fences or * submits work between steps 1 and 3 above. */ struct dma_buf_export_sync_file { /**


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