@@ -94,38 +94,75 @@ int RPiStream::queueBuffer(FrameBuffer *buffer)
{
/*
* A nullptr buffer implies an external stream, but no external
- * buffer has been supplied. So, pick one from the availableBuffers_
- * queue.
+ * buffer has been supplied in the Request. So, pick one from the
+ * availableBuffers_ queue.
*/
if (!buffer) {
if (availableBuffers_.empty()) {
- LOG(RPISTREAM, Warning) << "No buffers available for "
+ LOG(RPISTREAM, Info) << "No buffers available for "
<< name_;
- return -EINVAL;
+ /*
+ * Note that we need to queue an internal buffer as soon
+ * as one becomes available.
+ */
+ requestBuffers_.push(nullptr);
+ return 0;
}
buffer = availableBuffers_.front();
availableBuffers_.pop();
}
- LOG(RPISTREAM, Debug) << "Queuing buffer " << buffer->cookie()
- << " for " << name_;
+ /*
+ * If no earlier requests are pending to be queued we can go ahead and
+ * queue this buffer into the device.
+ */
+ if (requestBuffers_.empty())
+ return queueToDevice(buffer);
- int ret = dev_->queueBuffer(buffer);
- if (ret) {
- LOG(RPISTREAM, Error) << "Failed to queue buffer for "
- << name_;
- }
+ /*
+ * There are earlier Request buffers to be queued, so this buffer must go
+ * on the waiting list.
+ */
+ requestBuffers_.push(buffer);
- return ret;
+ return 0;
}
void RPiStream::returnBuffer(FrameBuffer *buffer)
{
/* This can only be called for external streams. */
- assert(external_);
+ ASSERT(external_);
+ /* Push this buffer back into the queue to be used again. */
availableBuffers_.push(buffer);
+
+ /*
+ * Do we have any Request buffers that are waiting to be queued?
+ * If so, do it now as availableBuffers_ will not be empty.
+ */
+ while (!requestBuffers_.empty()) {
+ FrameBuffer *buffer = requestBuffers_.front();
+
+ if (!buffer) {
+ /*
+ * We want to queue an internal buffer, but none
+ * are available. Can't do anything, quit the loop.
+ */
+ if (availableBuffers_.empty())
+ break;
+
+ /*
+ * We want to queue an internal buffer, and at least one
+ * is available.
+ */
+ buffer = availableBuffers_.front();
+ availableBuffers_.pop();
+ }
+
+ requestBuffers_.pop();
+ queueToDevice(buffer);
+ }
}
int RPiStream::queueAllBuffers()
@@ -155,10 +192,23 @@ void RPiStream::releaseBuffers()
void RPiStream::clearBuffers()
{
availableBuffers_ = std::queue<FrameBuffer *>{};
+ requestBuffers_ = std::queue<FrameBuffer *>{};
internalBuffers_.clear();
bufferList_.clear();
}
+int RPiStream::queueToDevice(FrameBuffer *buffer)
+{
+ LOG(RPISTREAM, Debug) << "Queuing buffer " << buffer->cookie()
+ << " for " << name_;
+
+ int ret = dev_->queueBuffer(buffer);
+ if (ret)
+ LOG(RPISTREAM, Error) << "Failed to queue buffer for "
+ << name_;
+ return ret;
+}
+
} /* namespace RPi */
} /* namespace libcamera */
@@ -57,6 +57,7 @@ public:
private:
void clearBuffers();
+ int queueToDevice(FrameBuffer *buffer);
/*
* Indicates that this stream is active externally, i.e. the buffers
@@ -73,7 +74,7 @@ private:
/* The actual device stream. */
std::unique_ptr<V4L2VideoDevice> dev_;
- /* All framebuffers associated with this device stream. */
+ /* All frame buffers associated with this device stream. */
std::vector<FrameBuffer *> bufferList_;
/*
@@ -83,6 +84,16 @@ private:
*/
std::queue<FrameBuffer *> availableBuffers_;
+ /*
+ * List of frame buffers that are to be queued into the device from a Request.
+ * A nullptr indicates any internal buffer can be used (from availableBuffers_),
+ * whereas a valid pointer indicates an external buffer to be queued.
+ *
+ * Ordering buffers to be queued is important here as it must match the
+ * requests coming from the application.
+ */
+ std::queue<FrameBuffer *> requestBuffers_;
+
/*
* This is a list of buffers exported internally. Need to keep this around
* as the stream needs to maintain ownership of these buffers.