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[35.221.247.27]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-724bef8da82sm2815815b3a.124.2024.11.20.21.54.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Nov 2024 21:54:42 -0800 (PST) From: Harvey Yang To: libcamera-devel@lists.libcamera.org Cc: Harvey Yang , Han-Lin Chen Subject: [PATCH v3 1/2] DmaBufAllocator: Add Dma Buffer synchronization function & helper class Date: Thu, 21 Nov 2024 05:51:31 +0000 Message-ID: <20241121055436.2502314-2-chenghaoyang@chromium.org> X-Mailer: git-send-email 2.47.0.338.g60cca15819-goog In-Reply-To: <20241121055436.2502314-1-chenghaoyang@chromium.org> References: <20241121055436.2502314-1-chenghaoyang@chromium.org> MIME-Version: 1.0 X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libcamera-devel-bounces@lists.libcamera.org Sender: "libcamera-devel" 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 --- .../libcamera/internal/dma_buf_allocator.h | 21 ++++++ src/libcamera/dma_buf_allocator.cpp | 75 +++++++++++++++++++ 2 files changed, 96 insertions(+) diff --git a/include/libcamera/internal/dma_buf_allocator.h b/include/libcamera/internal/dma_buf_allocator.h index d2a0a0d19..e4073f668 100644 --- a/include/libcamera/internal/dma_buf_allocator.h +++ b/include/libcamera/internal/dma_buf_allocator.h @@ -8,6 +8,7 @@ #pragma once #include +#include #include namespace libcamera { @@ -35,6 +36,26 @@ private: DmaBufAllocatorFlag type_; }; +class DmaSyncer final +{ +public: + enum class SyncType { + Read = 0, + Write, + ReadWrite, + }; + + explicit DmaSyncer(SharedFD fd, SyncType type = SyncType::ReadWrite); + + ~DmaSyncer(); + +private: + void sync(uint64_t step); + + SharedFD fd_; + uint64_t flags_ = 0; +}; + LIBCAMERA_FLAGS_ENABLE_OPERATORS(DmaBufAllocator::DmaBufAllocatorFlag) } /* namespace libcamera */ diff --git a/src/libcamera/dma_buf_allocator.cpp b/src/libcamera/dma_buf_allocator.cpp index be6efb89f..c1c2103d6 100644 --- a/src/libcamera/dma_buf_allocator.cpp +++ b/src/libcamera/dma_buf_allocator.cpp @@ -205,4 +205,79 @@ UniqueFD DmaBufAllocator::alloc(const char *name, std::size_t size) return allocFromHeap(name, size); } +/** + * \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 + */ + +/** + * \fn DmaSyncer::DmaSyncer(SharedFD fd, SyncType type = SyncType::ReadWrite) + * \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 */