libcamera: Fix maybe-uninitialized error

The gcc used in my current buildroot (Version 12.3) errors out with
-Wmaybe-uninitialized. Fix that.

Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>

src/ipa/libipa/exposure_mode_helper.cpp

@@ -166,7 +166,7 @@ ExposureModeHelper::splitExposure(utils::Duration exposure) const
 		return { minShutter_, minGain_, exposure / (minShutter_ * minGain_) };
 
 	utils::Duration shutter;
-	double stageGain;
+	double stageGain = 1.0;
 	double gain;
 
 	for (unsigned int stage = 0; stage < gains_.size(); stage++) {
@@ -201,12 +201,9 @@ ExposureModeHelper::splitExposure(utils::Duration exposure) const
 	 * From here on all we can do is max out the shutter time, followed by
 	 * the analogue gain. If we still haven't achieved the target we send
 	 * the rest of the exposure time to digital gain. If we were given no
-	 * stages to use then set stageGain to 1.0 so that shutter time is maxed
-	 * before gain touched at all.
+	 * stages to use then the default stageGain of 1.0 is used so that
+	 * shutter time is maxed before gain is touched at all.
 	 */
-	if (gains_.empty())
-		stageGain = 1.0;
-
 	shutter = clampShutter(exposure / clampGain(stageGain));
 	gain = clampGain(exposure / shutter);
 

src/ipa/rpi/controller/rpi/awb.cpp

@@ -122,7 +122,7 @@ int AwbConfig::read(const libcamera::YamlObject &params)
 		}
 		if (priors.empty()) {
 			LOG(RPiAwb, Error) << "AwbConfig: no AWB priors configured";
-			return ret;
+			return -EINVAL;
 		}
 	}
 	if (params.contains("modes")) {

src/libcamera/device_enumerator_sysfs.cpp

@@ -33,7 +33,7 @@ int DeviceEnumeratorSysfs::init()
 int DeviceEnumeratorSysfs::enumerate()
 {
 	struct dirent *ent;
-	DIR *dir;
+	DIR *dir = nullptr;
 
 	static const char * const sysfs_dirs[] = {
 		"/sys/subsystem/media/devices",

src/libcamera/pipeline/rpi/vc4/vc4.cpp

@@ -802,7 +802,7 @@ void Vc4CameraData::ispInputDequeue(FrameBuffer *buffer)
 void Vc4CameraData::ispOutputDequeue(FrameBuffer *buffer)
 {
 	RPi::Stream *stream = nullptr;
-	unsigned int index;
+	unsigned int index = 0;
 
 	if (!isRunning())
 		return;