[libcamera-devel] [PATCH v2 3/3] libcamera: pipeline: uvc: Use the device to validate formats

[Kieran Bingham]

UVC pipelines are highly variable, and we can not define their
configuration restrictions within the UVC pipeline handler directly.

Update the UVCCameraConfiguration to store the UVCCameraData (storing
a reference to the camera as a means of borrowing a reference to the
camera data).

We then validate the configuration by the tryFormat() operation on the
UVC V4L2Device.

Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
---
 src/libcamera/pipeline/uvcvideo.cpp | 36 +++++++++++++++++++++--------
 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
index 45260f34c8f5..df321c6e64a6 100644
--- a/src/libcamera/pipeline/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo.cpp
@@ -42,9 +42,18 @@ public:
 class UVCCameraConfiguration : public CameraConfiguration
 {
 public:
-	UVCCameraConfiguration();
+	UVCCameraConfiguration(Camera *camera, UVCCameraData *data);
 
 	Status validate() override;
+
+private:
+	/*
+	 * The UVCCameraConfiguration instance is guaranteed to be valid as long
+	 * as the corresponding Camera instance is valid. In order to borrow a
+	 * reference to the camera data, store a new reference to the camera.
+	 */
+	std::shared_ptr<Camera> camera_;
+	const UVCCameraData *data_;
 };
 
 class PipelineHandlerUVC : public PipelineHandler
@@ -76,9 +85,12 @@ private:
 	}
 };
 
-UVCCameraConfiguration::UVCCameraConfiguration()
+UVCCameraConfiguration::UVCCameraConfiguration(Camera *camera,
+					       UVCCameraData *data)
 	: CameraConfiguration()
 {
+	camera_ = camera->shared_from_this();
+	data_ = data;
 }
 
 CameraConfiguration::Status UVCCameraConfiguration::validate()
@@ -96,17 +108,20 @@ CameraConfiguration::Status UVCCameraConfiguration::validate()
 
 	StreamConfiguration &cfg = config_[0];
 
-	/* \todo: Validate the configuration against the device capabilities. */
-	const unsigned int pixelFormat = cfg.pixelFormat;
-	const Size size = cfg.size;
+	V4L2DeviceFormat format;
+	format.fourcc = cfg.pixelFormat;
+	format.size = cfg.size;
 
-	cfg.pixelFormat = V4L2_PIX_FMT_YUYV;
-	cfg.size = { 640, 480 };
+	/* Validate the format on the device. */
+	data_->video_->tryFormat(&format);
 
-	if (cfg.pixelFormat != pixelFormat || cfg.size != size) {
+	if (cfg.pixelFormat != format.fourcc || cfg.size != format.size) {
 		LOG(UVC, Debug)
 			<< "Adjusting configuration from " << cfg.toString()
-			<< " to " << cfg.size.toString() << "-YUYV";
+			<< " to " << format.toString();
+
+		cfg.pixelFormat = format.fourcc;
+		cfg.size = format.size;
 		status = Adjusted;
 	}
 
@@ -123,7 +138,8 @@ PipelineHandlerUVC::PipelineHandlerUVC(CameraManager *manager)
 CameraConfiguration *PipelineHandlerUVC::generateConfiguration(Camera *camera,
 	const StreamRoles &roles)
 {
-	CameraConfiguration *config = new UVCCameraConfiguration();
+	UVCCameraData *data = cameraData(camera);
+	CameraConfiguration *config = new UVCCameraConfiguration(camera, data);
 
 	if (roles.empty())
 		return config;
-- 
2.20.1