libcamera: uvcvideo: Fill stride and frameSize at config validation

Fill the stride and frameSize fields of the StreamConfiguration at
configuration validation time instead of at camera configuration time.
This allows applications to get the stride when trying a configuration
without modifying the active configuration of the camera.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/pipeline/uvcvideo/uvcvideo.cpp

@@ -53,9 +53,12 @@ public:
 class UVCCameraConfiguration : public CameraConfiguration
 {
 public:
-	UVCCameraConfiguration();
+	UVCCameraConfiguration(UVCCameraData *data);
 
 	Status validate() override;
+
+private:
+	UVCCameraData *data_;
 };
 
 class PipelineHandlerUVC : public PipelineHandler
@@ -89,8 +92,8 @@ private:
 	}
 };
 
-UVCCameraConfiguration::UVCCameraConfiguration()
-	: CameraConfiguration()
+UVCCameraConfiguration::UVCCameraConfiguration(UVCCameraData *data)
+	: CameraConfiguration(), data_(data)
 {
 }
 
@@ -141,6 +144,17 @@ CameraConfiguration::Status UVCCameraConfiguration::validate()
 
 	cfg.bufferCount = 4;
 
+	V4L2DeviceFormat format = {};
+	format.fourcc = data_->video_->toV4L2PixelFormat(cfg.pixelFormat);
+	format.size = cfg.size;
+
+	int ret = data_->video_->tryFormat(&format);
+	if (ret)
+		return Invalid;
+
+	cfg.stride = format.planes[0].bpl;
+	cfg.frameSize = format.planes[0].size;
+
 	return status;
 }
 
@@ -153,7 +167,7 @@ CameraConfiguration *PipelineHandlerUVC::generateConfiguration(Camera *camera,
 	const StreamRoles &roles)
 {
 	UVCCameraData *data = cameraData(camera);
-	CameraConfiguration *config = new UVCCameraConfiguration();
+	CameraConfiguration *config = new UVCCameraConfiguration(data);
 
 	if (roles.empty())
 		return config;
@@ -200,7 +214,6 @@ int PipelineHandlerUVC::configure(Camera *camera, CameraConfiguration *config)
 		return -EINVAL;
 
 	cfg.setStream(&data->stream_);
-	cfg.stride = format.planes[0].bpl;
 
 	return 0;
 }