Bug 1876895 - WebRTC backport: Video capture PipeWire: add support for DMABuf buffer type r=pehrsons,webrtc-reviewers

This is a simple backport of an WebRTC upstream change.

Upstream commit: 334e9133dcdecb5d00d991332e05c7b80ae26578

Differential Revision: https://phabricator.services.mozilla.com/D202929

third_party/libwebrtc/modules/desktop_capture/linux/wayland/shared_screencast_stream.cc

@@ -14,7 +14,6 @@
 #include <libdrm/drm_fourcc.h>
 #include <pipewire/pipewire.h>
 #include <spa/param/video/format-utils.h>
-#include <sys/mman.h>
 
 #include <vector>
 
@@ -49,33 +48,6 @@ constexpr int CursorMetaSize(int w, int h) {
 constexpr PipeWireVersion kDmaBufModifierMinVersion = {0, 3, 33};
 constexpr PipeWireVersion kDropSingleModifierMinVersion = {0, 3, 40};
 
-class ScopedBuf {
- public:
-  ScopedBuf() {}
-  ScopedBuf(uint8_t* map, int map_size, int fd)
-      : map_(map), map_size_(map_size), fd_(fd) {}
-  ~ScopedBuf() {
-    if (map_ != MAP_FAILED) {
-      munmap(map_, map_size_);
-    }
-  }
-
-  explicit operator bool() { return map_ != MAP_FAILED; }
-
-  void initialize(uint8_t* map, int map_size, int fd) {
-    map_ = map;
-    map_size_ = map_size;
-    fd_ = fd;
-  }
-
-  uint8_t* get() { return map_; }
-
- protected:
-  uint8_t* map_ = static_cast<uint8_t*>(MAP_FAILED);
-  int map_size_;
-  int fd_;
-};
-
 class SharedScreenCastStreamPrivate {
  public:
   SharedScreenCastStreamPrivate();

third_party/libwebrtc/modules/portal/pipewire_utils.h

@@ -11,6 +11,21 @@
 #ifndef MODULES_PORTAL_PIPEWIRE_UTILS_H_
 #define MODULES_PORTAL_PIPEWIRE_UTILS_H_
 
+#include <errno.h>
+#include <stdint.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+
+// static
+struct dma_buf_sync {
+  uint64_t flags;
+};
+#define DMA_BUF_SYNC_READ (1 << 0)
+#define DMA_BUF_SYNC_START (0 << 2)
+#define DMA_BUF_SYNC_END (1 << 2)
+#define DMA_BUF_BASE 'b'
+#define DMA_BUF_IOCTL_SYNC _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync)
+
 struct pw_thread_loop;
 
 namespace webrtc {
@@ -32,6 +47,66 @@ class PipeWireThreadLoopLock {
   pw_thread_loop* const loop_;
 };
 
+// We should synchronize DMA Buffer object access from CPU to avoid potential
+// cache incoherency and data loss.
+// See
+// https://01.org/linuxgraphics/gfx-docs/drm/driver-api/dma-buf.html#cpu-access-to-dma-buffer-objects
+static bool SyncDmaBuf(int fd, uint64_t start_or_end) {
+  struct dma_buf_sync sync = {0};
+
+  sync.flags = start_or_end | DMA_BUF_SYNC_READ;
+
+  while (true) {
+    int ret;
+    ret = ioctl(fd, DMA_BUF_IOCTL_SYNC, &sync);
+    if (ret == -1 && errno == EINTR) {
+      continue;
+    } else if (ret == -1) {
+      return false;
+    } else {
+      break;
+    }
+  }
+
+  return true;
+}
+
+class ScopedBuf {
+ public:
+  ScopedBuf() {}
+  ScopedBuf(uint8_t* map, int map_size, int fd, bool is_dma_buf = false)
+      : map_(map), map_size_(map_size), fd_(fd), is_dma_buf_(is_dma_buf) {}
+  ~ScopedBuf() {
+    if (map_ != MAP_FAILED) {
+      if (is_dma_buf_) {
+        SyncDmaBuf(fd_, DMA_BUF_SYNC_END);
+      }
+      munmap(map_, map_size_);
+    }
+  }
+
+  explicit operator bool() { return map_ != MAP_FAILED; }
+
+  void initialize(uint8_t* map, int map_size, int fd, bool is_dma_buf = false) {
+    map_ = map;
+    map_size_ = map_size;
+    is_dma_buf_ = is_dma_buf;
+    fd_ = fd;
+
+    if (is_dma_buf_) {
+      SyncDmaBuf(fd_, DMA_BUF_SYNC_START);
+    }
+  }
+
+  uint8_t* get() { return map_; }
+
+ protected:
+  uint8_t* map_ = static_cast<uint8_t*>(MAP_FAILED);
+  int map_size_;
+  int fd_;
+  bool is_dma_buf_;
+};
+
 }  // namespace webrtc
 
 #endif  // MODULES_PORTAL_PIPEWIRE_UTILS_H_

third_party/libwebrtc/modules/video_capture/linux/video_capture_pipewire.cc

@@ -178,8 +178,7 @@ int32_t VideoCaptureModulePipeWire::StartCapture(
   int res = pw_stream_connect(
       stream_, PW_DIRECTION_INPUT, node_id_,
       static_cast<enum pw_stream_flags>(PW_STREAM_FLAG_AUTOCONNECT |
-                                        PW_STREAM_FLAG_DONT_RECONNECT |
-                                        PW_STREAM_FLAG_MAP_BUFFERS),
+                                        PW_STREAM_FLAG_DONT_RECONNECT),
       params.data(), params.size());
   if (res != 0) {
     RTC_LOG(LS_ERROR) << "Could not connect to camera stream: "
@@ -312,11 +311,11 @@ void VideoCaptureModulePipeWire::OnFormatChanged(const struct spa_pod* format) {
                         0);
   }
 
+  const int buffer_types =
+      (1 << SPA_DATA_DmaBuf) | (1 << SPA_DATA_MemFd) | (1 << SPA_DATA_MemPtr);
   spa_pod_builder_add(
       &builder, SPA_PARAM_BUFFERS_buffers, SPA_POD_CHOICE_RANGE_Int(8, 1, 32),
-      SPA_PARAM_BUFFERS_dataType,
-      SPA_POD_CHOICE_FLAGS_Int((1 << SPA_DATA_MemFd) | (1 << SPA_DATA_MemPtr)),
-      0);
+      SPA_PARAM_BUFFERS_dataType, SPA_POD_CHOICE_FLAGS_Int(buffer_types), 0);
   params.push_back(
       static_cast<spa_pod*>(spa_pod_builder_pop(&builder, &frame)));
 
@@ -384,14 +383,15 @@ void VideoCaptureModulePipeWire::ProcessBuffers() {
   RTC_CHECK_RUNS_SERIALIZED(&capture_checker_);
 
   while (pw_buffer* buffer = pw_stream_dequeue_buffer(stream_)) {
+    spa_buffer* spaBuffer = buffer->buffer;
     struct spa_meta_header* h;
     h = static_cast<struct spa_meta_header*>(
-        spa_buffer_find_meta_data(buffer->buffer, SPA_META_Header, sizeof(*h)));
+        spa_buffer_find_meta_data(spaBuffer, SPA_META_Header, sizeof(*h)));
 
     struct spa_meta_videotransform* videotransform;
     videotransform =
         static_cast<struct spa_meta_videotransform*>(spa_buffer_find_meta_data(
-            buffer->buffer, SPA_META_VideoTransform, sizeof(*videotransform)));
+            spaBuffer, SPA_META_VideoTransform, sizeof(*videotransform)));
     if (videotransform) {
       VideoRotation rotation =
           VideorotationFromPipeWireTransform(videotransform->transform);
@@ -401,11 +401,35 @@ void VideoCaptureModulePipeWire::ProcessBuffers() {
 
     if (h->flags & SPA_META_HEADER_FLAG_CORRUPTED) {
       RTC_LOG(LS_INFO) << "Dropping corruped frame.";
-    } else {
-      IncomingFrame(static_cast<unsigned char*>(buffer->buffer->datas[0].data),
-                    buffer->buffer->datas[0].chunk->size,
-                    configured_capability_);
+      pw_stream_queue_buffer(stream_, buffer);
+      continue;
     }
+
+    if (spaBuffer->datas[0].type == SPA_DATA_DmaBuf ||
+        spaBuffer->datas[0].type == SPA_DATA_MemFd) {
+      ScopedBuf frame;
+      frame.initialize(
+          static_cast<uint8_t*>(
+              mmap(nullptr,
+                   spaBuffer->datas[0].maxsize + spaBuffer->datas[0].mapoffset,
+                   PROT_READ, MAP_PRIVATE, spaBuffer->datas[0].fd, 0)),
+          spaBuffer->datas[0].maxsize + spaBuffer->datas[0].mapoffset,
+          spaBuffer->datas[0].fd, spaBuffer->datas[0].type == SPA_DATA_DmaBuf);
+
+      if (!frame) {
+        RTC_LOG(LS_ERROR) << "Failed to mmap the memory: "
+                          << std::strerror(errno);
+        return;
+      }
+
+      IncomingFrame(
+          SPA_MEMBER(frame.get(), spaBuffer->datas[0].mapoffset, uint8_t),
+          spaBuffer->datas[0].chunk->size, configured_capability_);
+    } else {  // SPA_DATA_MemPtr
+      IncomingFrame(static_cast<uint8_t*>(spaBuffer->datas[0].data),
+                    spaBuffer->datas[0].chunk->size, configured_capability_);
+    }
+
     pw_stream_queue_buffer(stream_, buffer);
   }
 }

third_party/libwebrtc/moz-patch-stack/334e9133dc.no-op-cherry-pick-msg

@@ -0,0 +1 @@
+We cherry-picked this in bug 1876895.