[libcamera-devel] [PATCH] android: camera_device: Stop camera when re-configuring it

[Jacopo Mondi]

The Android camera device HAL3 specification does not require a
camera to go through any explicit close() call between configurations.
It is legit for a camera to be configured, a number of requests
processed and the re-configured again without any explicit stop.

The libcamera Android camera HAL starts the Camera at the first handled
request, and only stops it at camera close time. This mean, that two
camera configuration attempts part of the same streaming session are only
interleaved by capture requests handling.

The libcamera::Camera state machine requires the Camera to be stopped,
before any configuration take place, and this currently doesn't happen
in the camera HAL CameraDevice class.

Fix this by stopping the camera and the associated worker thread if
a configuration attempt is performed while the Camera is in running
state.

This patch fixes cros_camera_test:
Camera3PreviewTest/Camera3SinglePreviewTest.Camera3BasicPreviewTest/0

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>

---
Alternatively, the camera can be stopped at the very beginning of the
configureStream() function. But in that case the camera gets stopped
even if the configuration attempt fails (ie at validation time).

As both behaviour seems to be compliant with what Android expects, I decided
to stop the camera only if the configuration is valid.
---

 src/android/camera_device.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
index 675af5705055..2500994e2f6a 100644
--- a/src/android/camera_device.cpp
+++ b/src/android/camera_device.cpp
@@ -1341,8 +1341,15 @@ int CameraDevice::configureStreams(camera3_stream_configuration_t *stream_list)

 	/*
 	 * Once the CameraConfiguration has been adjusted/validated
-	 * it can be applied to the camera.
+	 * it can be applied to the camera, which has to be stopped if
+	 * in running state.
 	 */
+	if (running_) {
+		worker_.stop();
+		camera_->stop();
+		running_ = false;
+	}
+
 	int ret = camera_->configure(config_.get());
 	if (ret) {
 		LOG(HAL, Error) << "Failed to configure camera '"
--
2.29.1