Fix and improve sensor configuration file lookup

This commit addresses some of the sensor configuration lookup issues
- The CMake rule to use compile-time flag was opposite than intended
- The configuration file is now looked from all returned configuration
  paths, not just the last one which seemed a bit arbitrary
- Update related documentation, and while doing that also remove
  references to "N900" which  probably won't say that much to people
  these days (N900 was a smart phone released 12 years ago)

Pick-to: 6.2
Task-number: QTBUG-92505
Task-number: QTBUG-92512
Change-Id: Ib66ae052a815bbe3af32bd896931e65375e8546e
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

3 files changed, 23 insertions, 14 deletions

diff --git a/src/sensors/CMakeLists.txt b/src/sensors/CMakeLists.txt
index d57b7b62..beeda6a5 100644
--- a/src/sensors/CMakeLists.txt
+++ b/src/sensors/CMakeLists.txt
@@ -85,7 +85,7 @@ endif()
 ## Scopes:
 #####################################################################
 
-qt_internal_extend_target(Sensors CONDITION NOT SENSORS_CONFIG_PATH
+qt_internal_extend_target(Sensors CONDITION SENSORS_CONFIG_PATH
     DEFINES
         QTSENSORS_CONFIG_PATH="${SENSORS_CONFIG_PATH}"
 )
diff --git a/src/sensors/doc/src/qtsensors-backend.qdoc b/src/sensors/doc/src/qtsensors-backend.qdoc
index 7e62186d..752e8f92 100644
--- a/src/sensors/doc/src/qtsensors-backend.qdoc
+++ b/src/sensors/doc/src/qtsensors-backend.qdoc
@@ -89,9 +89,9 @@ An example follows.
 Sensors was designed so that multiple sensors could exist for a given type. Why?
 Consider this example.
 
-The N900 has an accelerometer built-in. It also features bluetooth and can pair
-with a gaming controller that features an accelerometer. To a developer writing
-a game these two devices are conceptually the same type.
+An Android device has an accelerometer built-in. It also features bluetooth and
+can pair with a gaming controller that features an accelerometer. To a developer
+writing a game these two devices are conceptually the same type.
 
 \section1 Default Sensor for a Type
 
@@ -109,21 +109,28 @@ instead.
 
 \section1 Sensors.conf
 
-The config file that determines the default sensor for a type is called Sensors.conf.
-If present, it is located in /etc/xdg/QtProject. It has the standard formatting
-of an ini file.
+The config file that determines the default sensor for a type is called
+\e Sensors.conf. The configuration file is looked for from \e QtProject
+directory under the directories given by
+QStandardPaths::standardLocations(QStandardPaths::ConfigLocation).
+An example of a complete file path is:
+\badcode
+/etc/xdg/QtProject/Sensors.conf
+\endcode
+The first found configuration file is used.
 
+The configuration file has the standard formatting of an ini file.
 The settings live in the Default group and the general format is:
 \code
 type = identifier
 \endcode
 
-An example: Sensors.conf ensures that the N900 accelerometer is used by default,
-not considering the order in which backends were registered.
+An example: Sensors.conf ensures that the \e sensorfw accelerometer is used by
+default, ignoring the order in which backends were registered.
 
 \code
 [Default]
-QAccelerometer = n900.accelerometer
+QAccelerometer=sensorfw.accelerometer
 \endcode
 
 If Sensors.conf specifies an identifier that is not registered, the system will
diff --git a/src/sensors/qsensormanager.cpp b/src/sensors/qsensormanager.cpp
index 43286467..95d9b6c0 100644
--- a/src/sensors/qsensormanager.cpp
+++ b/src/sensors/qsensormanager.cpp
@@ -96,10 +96,12 @@ public:
         QString config = QString::fromLocal8Bit(QTSENSORS_CONFIG_PATH);
 #else
         QStringList configs = QStandardPaths::standardLocations(QStandardPaths::ConfigLocation);
-        if (configs.count() == 0) return; // QStandardPaths is broken?
-        QString config = configs.at(configs.count()-1);
-        if (config.isEmpty()) return; // QStandardPaths is broken?
-        config += QLatin1String("/QtProject/Sensors.conf");
+        QString config;
+        for (const QString& c : configs) {
+            config = c + QLatin1String("/QtProject/Sensors.conf");
+            if (QFile::exists(config))
+                break;
+        }
 #endif
         qCDebug(sensorsCategory) << "Loading config from" << config;
         if (!QFile::exists(config)) {