libcamera: v4l2_device: Inherit from Loggable to print device node name

Automate printing of device node name in log messages by inheriting from
the Loggable class.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

src/libcamera/include/v4l2_device.h

@@ -15,6 +15,8 @@
 
 #include <libcamera/signal.h>
 
+#include "log.h"
+
 namespace libcamera {
 
 class Buffer;
@@ -76,7 +78,7 @@ public:
 	unsigned int planesCount;
 };
 
-class V4L2Device
+class V4L2Device : protected Loggable
 {
 public:
 	explicit V4L2Device(const std::string &deviceNode);
@@ -106,6 +108,9 @@ public:
 	int streamOn();
 	int streamOff();
 
+protected:
+	std::string logPrefix() const;
+
 private:
 	int getFormatSingleplane(V4L2DeviceFormat *format);
 	int setFormatSingleplane(V4L2DeviceFormat *format);