From c5abff62a0fa2fb1dfc77cf6e404c0fe57630dcf Mon Sep 17 00:00:00 2001
From: sladro <sladro@163.com>
Date: Mon, 5 Jan 2026 18:36:53 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BF=AE=E5=A4=8D=E8=8A=B1=E5=B1=8F?=
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---
 include/utils/dma_alloc.h                 |  4 ++++
 plugins/alarm/actions/snapshot_action.cpp |  5 +++++
 plugins/alarm/alarm_node.cpp              | 10 ++++++++++
 src/utils/dma_alloc.cpp                   | 22 ++++++++++++++++++++++
 4 files changed, 41 insertions(+)

diff --git a/include/utils/dma_alloc.h b/include/utils/dma_alloc.h
index 01fbf1d..6d1abd9 100644
--- a/include/utils/dma_alloc.h
+++ b/include/utils/dma_alloc.h
@@ -35,4 +35,8 @@ DmaBufferPtr DmaAlloc(size_t size);
 void DmaSyncStart(DmaBuffer* buf);
 void DmaSyncEnd(DmaBuffer* buf);
 
+// Sync DMA-BUF fd for CPU access (when only fd is available on Frame)
+void DmaSyncStartFd(int fd);
+void DmaSyncEndFd(int fd);
+
 }  // namespace rk3588
diff --git a/plugins/alarm/actions/snapshot_action.cpp b/plugins/alarm/actions/snapshot_action.cpp
index 59b46c5..e977c27 100644
--- a/plugins/alarm/actions/snapshot_action.cpp
+++ b/plugins/alarm/actions/snapshot_action.cpp
@@ -8,6 +8,8 @@
 #include <iostream>
 #include <sstream>
 
+#include "utils/dma_alloc.h"
+
 #if defined(RK3588_ENABLE_FFMPEG)
 extern "C" {
 #include <libavcodec/avcodec.h>
@@ -207,7 +209,10 @@ void SnapshotAction::Execute(AlarmEvent& event, std::shared_ptr<Frame> frame) {
         return;
     }
 
+    const int dma_fd = frame->dma_fd;
+    if (dma_fd >= 0) DmaSyncStartFd(dma_fd);
     auto jpeg_data = EncodeJpeg(frame);
+    if (dma_fd >= 0) DmaSyncEndFd(dma_fd);
     if (jpeg_data.empty()) {
         std::cerr << "[SnapshotAction] failed to encode JPEG\n";
         return;
diff --git a/plugins/alarm/alarm_node.cpp b/plugins/alarm/alarm_node.cpp
index 01535c8..812ec41 100644
--- a/plugins/alarm/alarm_node.cpp
+++ b/plugins/alarm/alarm_node.cpp
@@ -16,6 +16,7 @@
 #include "actions/http_action.h"
 #include "actions/snapshot_action.h"
 #include "actions/clip_action.h"
+#include "utils/dma_alloc.h"
 
 namespace rk3588 {
 
@@ -31,6 +32,15 @@ private:
         if (src->width <= 0 || src->height <= 0) return nullptr;
         if (!src->data) return nullptr;
 
+        const int dma_fd = src->dma_fd;
+        if (dma_fd >= 0) DmaSyncStartFd(dma_fd);
+        struct SyncGuard {
+            int fd;
+            ~SyncGuard() {
+                if (fd >= 0) DmaSyncEndFd(fd);
+            }
+        } guard{dma_fd};
+
         auto out = std::make_shared<Frame>();
         out->width = src->width;
         out->height = src->height;
diff --git a/src/utils/dma_alloc.cpp b/src/utils/dma_alloc.cpp
index 7326ff6..042b7dd 100644
--- a/src/utils/dma_alloc.cpp
+++ b/src/utils/dma_alloc.cpp
@@ -260,4 +260,26 @@ void DmaSyncEnd(DmaBuffer* buf) {
 #endif
 }
 
+void DmaSyncStartFd(int fd) {
+#if defined(__linux__)
+    if (fd < 0) return;
+    dma_buf_sync sync{};
+    sync.flags = DMA_BUF_SYNC_START | DMA_BUF_SYNC_READ | DMA_BUF_SYNC_WRITE;
+    ioctl(fd, DMA_BUF_IOCTL_SYNC, &sync);
+#else
+    (void)fd;
+#endif
+}
+
+void DmaSyncEndFd(int fd) {
+#if defined(__linux__)
+    if (fd < 0) return;
+    dma_buf_sync sync{};
+    sync.flags = DMA_BUF_SYNC_END | DMA_BUF_SYNC_READ | DMA_BUF_SYNC_WRITE;
+    ioctl(fd, DMA_BUF_IOCTL_SYNC, &sync);
+#else
+    (void)fd;
+#endif
+}
+
 }  // namespace rk3588