libcamera: pipeline: Move tuning file override handling to IPAProxy

The rkisp1 and rpi pipeline handlers duplicate code to handle the
LIBCAMERA_RKISP1_TUNING_FILE and LIBCAMERA_RPI_TUNING_FILE environment
variables that override tuning file selection. Move the common code to
IPAProxy::configurationFile() to avoid the duplication, and make the
feature available to all pipeline handlers with the same behaviour.

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

Documentation/environment_variables.rst

@@ -57,8 +57,8 @@ LIBCAMERA_RPI_CONFIG_FILE
 
    Example value: ``/usr/local/share/libcamera/pipeline/rpi/vc4/minimal_mem.yaml``
 
-LIBCAMERA_RPI_TUNING_FILE
+LIBCAMERA_<NAME>_TUNING_FILE
-   Define a custom JSON tuning file to use in the Raspberry Pi.
+   Define a custom IPA tuning file to use with the pipeline handler `NAME`.
 
    Example value: ``/usr/local/share/libcamera/ipa/rpi/vc4/custom_sensor.json``
 

src/libcamera/ipa_proxy.cpp

@@ -98,16 +98,33 @@ IPAProxy::~IPAProxy()
 std::string IPAProxy::configurationFile(const std::string &name,
 					const std::string &fallbackName) const
 {
-	struct stat statbuf;
-	int ret;
-
 	/*
 	 * The IPA module name can be used as-is to build directory names as it
 	 * has been validated when loading the module.
 	 */
-	std::string ipaName = ipam_->info().name;
+	const std::string ipaName = ipam_->info().name;
 
-	/* Check the environment variable first. */
+	/*
+	 * Start with any user override through the module-specific environment
+	 * variable. Use the name of the IPA module up to the first '/' to
+	 * construct the variable name.
+	 */
+	std::string ipaEnvName = ipaName.substr(0, ipaName.find('/'));
+	std::transform(ipaEnvName.begin(), ipaEnvName.end(), ipaEnvName.begin(),
+		       [](unsigned char c) { return std::toupper(c); });
+	ipaEnvName = "LIBCAMERA_" + ipaEnvName + "_TUNING_FILE";
+
+	char const *configFromEnv = utils::secure_getenv(ipaEnvName.c_str());
+	if (configFromEnv && *configFromEnv == '\0')
+		return { configFromEnv };
+
+	struct stat statbuf;
+	int ret;
+
+	/*
+	 * Check the directory pointed to by the IPA config path environment
+	 * variable next.
+	 */
 	const char *confPaths = utils::secure_getenv("LIBCAMERA_IPA_CONFIG_PATH");
 	if (confPaths) {
 		for (const auto &dir : utils::split(confPaths, ":")) {

src/libcamera/pipeline/rkisp1/rkisp1.cpp

@@ -380,18 +380,9 @@ int RkISP1CameraData::loadIPA(unsigned int hwRevision)
 	ipa_->paramsComputed.connect(this, &RkISP1CameraData::paramsComputed);
 	ipa_->metadataReady.connect(this, &RkISP1CameraData::metadataReady);
 
-	/*
+	/* The IPA tuning file is made from the sensor name. */
-	 * The API tuning file is made from the sensor name unless the
+	std::string ipaTuningFile =
-	 * environment variable overrides it.
+		ipa_->configurationFile(sensor_->model() + ".yaml", "uncalibrated.yaml");
-	 */
-	std::string ipaTuningFile;
-	char const *configFromEnv = utils::secure_getenv("LIBCAMERA_RKISP1_TUNING_FILE");
-	if (!configFromEnv || *configFromEnv == '\0') {
-		ipaTuningFile =
-			ipa_->configurationFile(sensor_->model() + ".yaml", "uncalibrated.yaml");
-	} else {
-		ipaTuningFile = std::string(configFromEnv);
-	}
 
 	IPACameraSensorInfo sensorInfo{};
 	int ret = sensor_->sensorInfo(&sensorInfo);

src/libcamera/pipeline/rpi/common/pipeline_base.cpp

@@ -1156,20 +1156,11 @@ int CameraData::loadIPA(ipa::RPi::InitResult *result)
 	if (!ipa_)
 		return -ENOENT;
 
-	/*
+	/* The configuration (tuning file) is made from the sensor name. */
-	 * The configuration (tuning file) is made from the sensor name unless
+	std::string model = sensor_->model();
-	 * the environment variable overrides it.
+	if (isMonoSensor(sensor_))
-	 */
+		model += "_mono";
-	std::string configurationFile;
+	std::string configurationFile = ipa_->configurationFile(model + ".json");
-	char const *configFromEnv = utils::secure_getenv("LIBCAMERA_RPI_TUNING_FILE");
-	if (!configFromEnv || *configFromEnv == '\0') {
-		std::string model = sensor_->model();
-		if (isMonoSensor(sensor_))
-			model += "_mono";
-		configurationFile = ipa_->configurationFile(model + ".json");
-	} else {
-		configurationFile = std::string(configFromEnv);
-	}
 
 	IPASettings settings(configurationFile, sensor_->model());
 	ipa::RPi::InitParams params;