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authorPaul Elder <paul.elder@ideasonboard.com>2020-06-16 16:40:34 +0900
committerPaul Elder <paul.elder@ideasonboard.com>2020-06-25 23:47:13 +0900
commit566ccd75cafd0bd9d60d350405ca7d337786ae39 (patch)
tree77208d0cfc8c0eec0886bc1b5a5ba73c6efdba46 /src
parentf155e638168cb0d6cbd9dde8748301fa12a0736f (diff)
v4l2: v4l2_camera: Don't use libcamera::Semaphore for available buffers
In V4L2, a blocked dqbuf should not not also block a streamoff. This means that on streamoff, the blocked dqbuf must return (with error). We cannot do this with the libcamera semaphore, so pull out the necessary components of a semaphore, and put them into V4L2Camera, so that dqbuf from V4L2CameraProxy can wait on a disjunct condition of the availability of the semaphore or the stopping of the stream. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Diffstat (limited to 'src')
-rw-r--r--src/v4l2/v4l2_camera.cpp34
-rw-r--r--src/v4l2/v4l2_camera.h9
-rw-r--r--src/v4l2/v4l2_camera_proxy.cpp11
3 files changed, 47 insertions, 7 deletions
diff --git a/src/v4l2/v4l2_camera.cpp b/src/v4l2/v4l2_camera.cpp
index 177b1ea5..f7df9b85 100644
--- a/src/v4l2/v4l2_camera.cpp
+++ b/src/v4l2/v4l2_camera.cpp
@@ -18,7 +18,7 @@ LOG_DECLARE_CATEGORY(V4L2Compat);
V4L2Camera::V4L2Camera(std::shared_ptr<Camera> camera)
: camera_(camera), isRunning_(false), bufferAllocator_(nullptr),
- efd_(-1)
+ efd_(-1), bufferAvailableCount_(0)
{
camera_->requestCompleted.connect(this, &V4L2Camera::requestComplete);
}
@@ -100,7 +100,11 @@ void V4L2Camera::requestComplete(Request *request)
if (ret != sizeof(data))
LOG(V4L2Compat, Error) << "Failed to signal eventfd POLLIN";
- bufferSema_.release();
+ {
+ MutexLocker locker(bufferMutex_);
+ bufferAvailableCount_++;
+ }
+ bufferCV_.notify_all();
}
int V4L2Camera::configure(StreamConfiguration *streamConfigOut,
@@ -192,7 +196,11 @@ int V4L2Camera::streamOff()
if (ret < 0)
return ret == -EACCES ? -EBUSY : ret;
- isRunning_ = false;
+ {
+ MutexLocker locker(bufferMutex_);
+ isRunning_ = false;
+ }
+ bufferCV_.notify_all();
return 0;
}
@@ -228,6 +236,26 @@ int V4L2Camera::qbuf(unsigned int index)
return 0;
}
+void V4L2Camera::waitForBufferAvailable()
+{
+ MutexLocker locker(bufferMutex_);
+ bufferCV_.wait(locker, [&] {
+ return bufferAvailableCount_ >= 1 || !isRunning_;
+ });
+ if (isRunning_)
+ bufferAvailableCount_--;
+}
+
+bool V4L2Camera::isBufferAvailable()
+{
+ MutexLocker locker(bufferMutex_);
+ if (bufferAvailableCount_ < 1)
+ return false;
+
+ bufferAvailableCount_--;
+ return true;
+}
+
bool V4L2Camera::isRunning()
{
return isRunning_;
diff --git a/src/v4l2/v4l2_camera.h b/src/v4l2/v4l2_camera.h
index ee53c2b0..515e9060 100644
--- a/src/v4l2/v4l2_camera.h
+++ b/src/v4l2/v4l2_camera.h
@@ -57,9 +57,10 @@ public:
int qbuf(unsigned int index);
- bool isRunning();
+ void waitForBufferAvailable();
+ bool isBufferAvailable();
- Semaphore bufferSema_;
+ bool isRunning();
private:
void requestComplete(Request *request);
@@ -76,6 +77,10 @@ private:
std::deque<std::unique_ptr<Buffer>> completedBuffers_;
int efd_;
+
+ Mutex bufferMutex_;
+ std::condition_variable bufferCV_;
+ unsigned int bufferAvailableCount_;
};
#endif /* __V4L2_CAMERA_H__ */
diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
index 7bf9e7f8..a222795d 100644
--- a/src/v4l2/v4l2_camera_proxy.cpp
+++ b/src/v4l2/v4l2_camera_proxy.cpp
@@ -588,10 +588,17 @@ int V4L2CameraProxy::vidioc_dqbuf(V4L2CameraFile *file, struct v4l2_buffer *arg)
return -EINVAL;
if (!file->nonBlocking())
- vcam_->bufferSema_.acquire();
- else if (!vcam_->bufferSema_.tryAcquire())
+ vcam_->waitForBufferAvailable();
+ else if (!vcam_->isBufferAvailable())
return -EAGAIN;
+ /*
+ * We need to check here again in case stream was turned off while we
+ * were blocked on waitForBufferAvailable().
+ */
+ if (!vcam_->isRunning())
+ return -EINVAL;
+
updateBuffers();
struct v4l2_buffer &buf = buffers_[currentBuf_];