libcamera: v4l2_subdevice: Inherit from Loggable

Prefix the V4L2Subdevice error messages with the name of the entity.
Remove the manually printed name from log messages where it was used and
standardize error messages while at there.

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/include/v4l2_subdevice.h

@@ -9,6 +9,7 @@
 
 #include <string>
 
+#include "log.h"
 #include "media_object.h"
 
 namespace libcamera {
@@ -21,7 +22,7 @@ struct V4L2SubdeviceFormat {
 	uint32_t height;
 };
 
-class V4L2Subdevice
+class V4L2Subdevice : protected Loggable
 {
 public:
 	explicit V4L2Subdevice(const MediaEntity *entity);
@@ -41,6 +42,9 @@ public:
 	int getFormat(unsigned int pad, V4L2SubdeviceFormat *format);
 	int setFormat(unsigned int pad, V4L2SubdeviceFormat *format);
 
+protected:
+	std::string logPrefix() const;
+
 private:
 	int setSelection(unsigned int pad, unsigned int target,
 			 Rectangle *rect);

src/libcamera/v4l2_subdevice.cpp

@@ -154,6 +154,11 @@ void V4L2Subdevice::close()
  * \return The name of the media entity the subdevice is associated to
  */
 
+std::string V4L2Subdevice::logPrefix() const
+{
+	return "'" + deviceName() + "'";
+}
+
 /**
  * \brief Set a crop rectangle on one of the V4L2 subdevice pads
  * \param[in] pad The 0-indexed pad number the rectangle is to be applied to
@@ -196,7 +201,7 @@ int V4L2Subdevice::getFormat(unsigned int pad, V4L2SubdeviceFormat *format)
 		ret = -errno;
 		LOG(V4L2Subdev, Error)
 			<< "Unable to get format on pad " << pad
-			<< " of " << deviceNode() << ": " << strerror(-ret);
+			<< ": " << strerror(-ret);
 		return ret;
 	}
 
@@ -231,7 +236,8 @@ int V4L2Subdevice::setFormat(unsigned int pad, V4L2SubdeviceFormat *format)
 	if (ret) {
 		ret = -errno;
 		LOG(V4L2Subdev, Error)
-			<< "Unable to set format: " << strerror(-ret);
+			<< "Unable to set format on pad " << pad
+			<< ": " << strerror(-ret);
 		return ret;
 	}
 
@@ -262,8 +268,7 @@ int V4L2Subdevice::setSelection(unsigned int pad, unsigned int target,
 		ret = -errno;
 		LOG(V4L2Subdev, Error)
 			<< "Unable to set rectangle " << target << " on pad "
-			<< pad << " of " << deviceNode() << ": "
-			<< strerror(-ret);
+			<< pad << ": " << strerror(-ret);
 		return ret;
 	}