treewide: Remove top-level const from return types

Top-level `const` qualifiers are not useful, so avoid them. This is done
either by simply removing the top-level `const`, or making the function
return a reference to const where that is appropriate.

Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Stefan Klug <stefan.klug@ideasonboard.com>

src/apps/cam/drm.h

@@ -97,9 +97,9 @@ public:
 
 	bool isImmutable() const { return flags_ & DRM_MODE_PROP_IMMUTABLE; }
 
-	const std::vector<uint64_t> values() const { return values_; }
+	const std::vector<uint64_t> &values() const { return values_; }
 	const std::map<uint32_t, std::string> &enums() const { return enums_; }
-	const std::vector<uint32_t> blobs() const { return blobs_; }
+	const std::vector<uint32_t> &blobs() const { return blobs_; }
 
 private:
 	Type type_;

src/ipa/libipa/histogram.h

@@ -36,7 +36,7 @@ public:
 	}
 
 	size_t bins() const { return cumulative_.size() - 1; }
-	const Span<const uint64_t> data() const { return cumulative_; }
+	Span<const uint64_t> data() const { return cumulative_; }
 	uint64_t total() const { return cumulative_[cumulative_.size() - 1]; }
 	uint64_t cumulativeFrequency(double bin) const;
 	double quantile(double q, uint32_t first = 0, uint32_t last = UINT_MAX) const;

src/libcamera/geometry.cpp

@@ -53,7 +53,7 @@ namespace libcamera {
  * \brief Assemble and return a string describing the point
  * \return A string describing the point
  */
-const std::string Point::toString() const
+std::string Point::toString() const
 {
 	std::stringstream ss;
 	ss << *this;
@@ -133,7 +133,7 @@ std::ostream &operator<<(std::ostream &out, const Point &p)
  * \brief Assemble and return a string describing the size
  * \return A string describing the size
  */
-const std::string Size::toString() const
+std::string Size::toString() const
 {
 	std::stringstream ss;
 	ss << *this;
@@ -676,7 +676,7 @@ std::ostream &operator<<(std::ostream &out, const SizeRange &sr)
  * \brief Assemble and return a string describing the rectangle
  * \return A string describing the Rectangle
  */
-const std::string Rectangle::toString() const
+std::string Rectangle::toString() const
 {
 	std::stringstream ss;
 	ss << *this;

src/libcamera/pipeline/ipu3/ipu3.cpp

@@ -105,7 +105,7 @@ public:
 	Status validate() override;
 
 	const StreamConfiguration &cio2Format() const { return cio2Configuration_; }
-	const ImgUDevice::PipeConfig imguConfig() const { return pipeConfig_; }
+	const ImgUDevice::PipeConfig &imguConfig() const { return pipeConfig_; }
 
 	/* Cache the combinedTransform_ that will be applied to the sensor */
 	Transform combinedTransform_;

src/libcamera/pipeline/mali-c55/mali-c55.cpp

@@ -101,8 +101,8 @@ public:
 	int loadIPA();
 
 	/* Deflect these functionalities to either TPG or CameraSensor. */
-	const std::vector<Size> sizes(unsigned int mbusCode) const;
-	const Size resolution() const;
+	std::vector<Size> sizes(unsigned int mbusCode) const;
+	Size resolution() const;
 
 	int pixfmtToMbusCode(const PixelFormat &pixFmt) const;
 	const PixelFormat &bestRawFormat() const;
@@ -195,7 +195,7 @@ void MaliC55CameraData::setSensorControls(const ControlList &sensorControls)
 	delayedCtrls_->push(sensorControls);
 }
 
-const std::vector<Size> MaliC55CameraData::sizes(unsigned int mbusCode) const
+std::vector<Size> MaliC55CameraData::sizes(unsigned int mbusCode) const
 {
 	if (sensor_)
 		return sensor_->sizes(mbusCode);
@@ -218,7 +218,7 @@ const std::vector<Size> MaliC55CameraData::sizes(unsigned int mbusCode) const
 	return sizes;
 }
 
-const Size MaliC55CameraData::resolution() const
+Size MaliC55CameraData::resolution() const
 {
 	if (sensor_)
 		return sensor_->resolution();

src/libcamera/v4l2_subdevice.cpp

@@ -923,7 +923,7 @@ const MediaBusFormatInfo &MediaBusFormatInfo::info(uint32_t code)
  * \brief Assemble and return a string describing the format
  * \return A string describing the V4L2SubdeviceFormat
  */
-const std::string V4L2SubdeviceFormat::toString() const
+std::string V4L2SubdeviceFormat::toString() const
 {
 	std::stringstream ss;
 	ss << *this;

src/libcamera/v4l2_videodevice.cpp

@@ -429,7 +429,7 @@ bool V4L2BufferCache::Entry::operator==(const FrameBuffer &buffer) const
  * \brief Assemble and return a string describing the format
  * \return A string describing the V4L2DeviceFormat
  */
-const std::string V4L2DeviceFormat::toString() const
+std::string V4L2DeviceFormat::toString() const
 {
 	std::stringstream ss;
 	ss << *this;