2 files changed, 67 insertions, 1 deletions

diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
index 1db263cf..eb84d9eb 100644
--- a/src/libcamera/camera_sensor.cpp
+++ b/src/libcamera/camera_sensor.cpp
@@ -670,15 +670,30 @@ V4L2SubdeviceFormat CameraSensor::getFormat(const std::vector<unsigned int> &mbu
 /**
  * \brief Set the sensor output format
  * \param[in] format The desired sensor output format
+ *
+ * The ranges of any controls associated with the sensor are also updated.
+ *
  * \return 0 on success or a negative error code otherwise
  */
 int CameraSensor::setFormat(V4L2SubdeviceFormat *format)
 {
-	return subdev_->setFormat(pad_, format);
+	int ret = subdev_->setFormat(pad_, format);
+	if (ret)
+		return ret;
+
+	updateControlInfo();
+	return 0;
 }
 
 /**
  * \brief Retrieve the supported V4L2 controls and their information
+ *
+ * Control information is updated automatically to reflect the current sensor
+ * configuration when the setFormat() function is called, without invalidating
+ * any iterator on the ControlInfoMap. A manual update can also be forced by
+ * calling the updateControlInfo() function for pipeline handlers that change
+ * the sensor configuration wihtout using setFormat().
+ *
  * \return A map of the V4L2 controls supported by the sensor
  */
 const ControlInfoMap &CameraSensor::controls() const
@@ -764,6 +779,10 @@ int CameraSensor::setControls(ControlList *ctrls)
  * Sensor information is only available for raw sensors. When called for a YUV
  * sensor, this function returns -EINVAL.
  *
+ * Pipeline handlers that do not change the sensor format using the setFormat()
+ * method may need to call updateControlInfo() beforehand, to ensure all the
+ * control ranges are up to date.
+ *
  * \return 0 on success, a negative error code otherwise
  */
 int CameraSensor::sensorInfo(CameraSensorInfo *info) const
@@ -835,6 +854,16 @@ int CameraSensor::sensorInfo(CameraSensorInfo *info) const
 	return 0;
 }
 
+/**
+ * \fn void CameraSensor::updateControlInfo()
+ * \brief Update the sensor's ControlInfoMap in case they have changed
+ * \sa V4L2Device::updateControlInfo()
+ */
+void CameraSensor::updateControlInfo()
+{
+	subdev_->updateControlInfo();
+}
+
 std::string CameraSensor::logPrefix() const
 {
 	return "'" + entity_->name() + "'";
diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
index 397029ac..515cbdfe 100644
--- a/src/libcamera/v4l2_device.cpp
+++ b/src/libcamera/v4l2_device.cpp
@@ -511,6 +511,43 @@ void V4L2Device::listControls()
 	controls_ = std::move(ctrls);
 }
 
+/**
+* \brief Update the information for all device controls
+ *
+ * The V4L2Device class caches information about all controls supported by the
+ * device and exposes it through the controls() and controlInfo() functions.
+ * Control information may change at runtime, for instance when formats on a
+ * subdev are modified. When this occurs, this function can be used to refresh
+ * control information. The information is refreshed in-place, all pointers to
+ * v4l2_query_ext_ctrl instances previously returned by controlInfo() and
+ * iterators to the ControlInfoMap returned by controls() remain valid.
+ *
+ * Note that control information isn't refreshed automatically is it may be an
+ * expensive operation. The V4L2Device users are responsible for calling this
+ * function when required, based on their usage pattern of the class.
+ */
+void V4L2Device::updateControlInfo()
+{
+	for (auto &[controlId, info] : controls_) {
+		unsigned int id = controlId->id();
+
+		/*
+		 * Assume controlInfo_ has a corresponding entry, as it has been
+		 * generated by listControls().
+		 */
+		struct v4l2_query_ext_ctrl &ctrl = controlInfo_[id];
+
+		if (ioctl(VIDIOC_QUERY_EXT_CTRL, &ctrl)) {
+			LOG(V4L2, Debug)
+				<< "Could not refresh control "
+				<< utils::hex(id);
+			continue;
+		}
+
+		info = V4L2ControlInfo(ctrl);
+	}
+}
+
 /*
  * \brief Update the value of the first \a count V4L2 controls in \a ctrls using
  * values in \a v4l2Ctrls