From 39482d59fe7160740ea5dd61f3ed965a88d848ce Mon Sep 17 00:00:00 2001 From: Harvey Yang Date: Thu, 21 Nov 2024 05:51:31 +0000 Subject: DmaBufAllocator: Add Dma Buffer synchronization function & helper class To synchronize CPU access with mmap and hardware access on DMA buffers, using `DMA_BUF_IOCTL_SYNC` is required. This patch adds a function and a helper class to allow users to sync buffers more easily. Signed-off-by: Han-Lin Chen Co-developed-by: Harvey Yang Signed-off-by: Harvey Yang Reviewed-by: Milan Zamazal Reviewed-by: Kieran Bingham Signed-off-by: Kieran Bingham --- src/libcamera/dma_buf_allocator.cpp | 74 +++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) (limited to 'src') diff --git a/src/libcamera/dma_buf_allocator.cpp b/src/libcamera/dma_buf_allocator.cpp index 262eb53a..3cc52f96 100644 --- a/src/libcamera/dma_buf_allocator.cpp +++ b/src/libcamera/dma_buf_allocator.cpp @@ -262,4 +262,78 @@ DmaBufAllocator::createBuffer(std::string name, return std::make_unique(planes); } +/** + * \class DmaSyncer + * \brief Helper class for dma-buf's synchronization + * + * This class wraps a userspace dma-buf's synchronization process with an + * object's lifetime. + * + * It's used when the user needs to access a dma-buf with CPU, mostly mapped + * with MappedFrameBuffer, so that the buffer is synchronized between CPU and + * ISP. + */ + +/** + * \enum DmaSyncer::SyncType + * \brief Read and/or write access via the CPU map + * \var DmaSyncer::Read + * \brief Indicates that the mapped dma-buf will be read by the client via the + * CPU map + * \var DmaSyncer::Write + * \brief Indicates that the mapped dm-buf will be written by the client via the + * CPU map + * \var DmaSyncer::ReadWrite + * \brief Indicates that the mapped dma-buf will be read and written by the + * client via the CPU map + */ + +/** + * \brief Construct a DmaSyncer with a dma-buf's fd and the access type + * \param[in] fd The dma-buf's file descriptor to synchronize + * \param[in] type Read and/or write access via the CPU map + */ +DmaSyncer::DmaSyncer(SharedFD fd, SyncType type) + : fd_(fd) +{ + switch (type) { + case SyncType::Read: + flags_ = DMA_BUF_SYNC_READ; + break; + case SyncType::Write: + flags_ = DMA_BUF_SYNC_WRITE; + break; + case SyncType::ReadWrite: + flags_ = DMA_BUF_SYNC_RW; + break; + } + + sync(DMA_BUF_SYNC_START); +} + +DmaSyncer::~DmaSyncer() +{ + sync(DMA_BUF_SYNC_END); +} + +void DmaSyncer::sync(uint64_t step) +{ + struct dma_buf_sync sync = { + .flags = flags_ | step + }; + + int ret; + do { + ret = ioctl(fd_.get(), DMA_BUF_IOCTL_SYNC, &sync); + } while (ret && (errno == EINTR || errno == EAGAIN)); + + if (ret) { + ret = errno; + LOG(DmaBufAllocator, Error) + << "Unable to sync dma fd: " << fd_.get() + << ", err: " << strerror(ret) + << ", flags: " << sync.flags; + } +} + } /* namespace libcamera */ -- cgit v1.2.1