[libcamera-devel] [PATCH v3 15/22] v4l2: v4l2_camera_proxy: Reset buffer flags on reqbufs 0

[Paul Elder]

Clear the queued and done buffer flags on VIDIOC_REQBUFS with count = 0
if the stream is not on. If the stream is on and reqbufs is called with
count = 0, return -EBUSY.

Note that this is contrary to what the V4L2 docs say (reqbufs 0 when
streaming should also streamoff), but it is how the V4L2 implementation
works. v4l2-compliance doesn't seem to care either way, however, so we
cater to the implementation.

Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>

---
Changes in v3:
- don't streamoff in reqbufs 0; return -EBUSY instead

Changes in v2:
- call only the necessary components, instead of
  V4L2CameraProxy::vidioc_streamoff
---
 src/v4l2/v4l2_camera_proxy.cpp | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
index 06fef21..fa58585 100644
--- a/src/v4l2/v4l2_camera_proxy.cpp
+++ b/src/v4l2/v4l2_camera_proxy.cpp
@@ -444,11 +444,6 @@ int V4L2CameraProxy::freeBuffers()
 {
 	LOG(V4L2Compat, Debug) << "Freeing libcamera bufs";
 
-	int ret = vcam_->streamOff();
-	if (ret < 0) {
-		LOG(V4L2Compat, Error) << "Failed to stop stream";
-		return ret;
-	}
 	vcam_->freeBuffers();
 	bufferCount_ = 0;
 
@@ -476,6 +471,12 @@ int V4L2CameraProxy::vidioc_reqbufs(V4L2CameraFile *file, struct v4l2_requestbuf
 	memset(arg->reserved, 0, sizeof(arg->reserved));
 
 	if (arg->count == 0) {
+		if (vcam_->isRunning())
+			return -EBUSY;
+
+		for (struct v4l2_buffer &buf : buffers_)
+			buf.flags &= ~(V4L2_BUF_FLAG_QUEUED | V4L2_BUF_FLAG_DONE);
+
 		release(file);
 		return freeBuffers();
 	}
-- 
2.27.0