[libcamera-devel] [PATCH v3 2/6] libcamera: camera_sensor: Validate driver support

[Jacopo Mondi]

The CameraSensor class requires the sensor driver to report
information through V4L2 controls and through the V4L2 selection API,
and uses that information to register Camera properties and to
construct CameraSensorInfo class instances to provide them to the IPA.

Currently, validation of the kernel support happens each time a
feature is requested, with slighly similar debug/error messages
output to the user in case a feature is not supported.

Rationalize this by:
- Validate the sensor driver requirements in a single function
- Expand the debug output when a property gets defaulted to a value
- Be more verbose when constructing CameraSensorInfo is not possible

Reviewed-by: Paul Elder <paul.elder at ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 include/libcamera/internal/camera_sensor.h |   1 +
 src/libcamera/camera_sensor.cpp            | 117 ++++++++++++++++++---
 2 files changed, 102 insertions(+), 16 deletions(-)

diff --git a/include/libcamera/internal/camera_sensor.h b/include/libcamera/internal/camera_sensor.h
index f80d836161a5..aee10aa6e3c7 100644
--- a/include/libcamera/internal/camera_sensor.h
+++ b/include/libcamera/internal/camera_sensor.h
@@ -69,6 +69,7 @@ protected:
 
 private:
 	int generateId();
+	int validateSensorDriver();
 	int initProperties();
 
 	const MediaEntity *entity_;
diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
index e786821d4ba2..a1f1256bd6f4 100644
--- a/src/libcamera/camera_sensor.cpp
+++ b/src/libcamera/camera_sensor.cpp
@@ -207,6 +207,10 @@ int CameraSensor::init()
 	 */
 	resolution_ = sizes_.back();
 
+	ret = validateSensorDriver();
+	if (ret)
+		return ret;
+
 	ret = initProperties();
 	if (ret)
 		return ret;
@@ -214,6 +218,86 @@ int CameraSensor::init()
 	return 0;
 }
 
+int CameraSensor::validateSensorDriver()
+{
+	/*
+	 * Make sure the sensor driver supports the mandatory controls
+	 * required by the CameraSensor class.
+	 * - V4L2_CID_PIXEL_RATE is used to calculate the sensor timings
+	 * - V4L2_CID_HBLANK is used to calculate the line length
+	 */
+	const std::vector<uint32_t> mandatoryControls{
+		V4L2_CID_PIXEL_RATE,
+		V4L2_CID_HBLANK,
+	};
+
+	ControlList ctrls = subdev_->getControls(mandatoryControls);
+	if (ctrls.empty()) {
+		LOG(CameraSensor, Error)
+			<< "Mandatory V4L2 controls not available";
+		LOG(CameraSensor, Error)
+			<< "The sensor kernel driver needs to be fixed";
+		LOG(CameraSensor, Error)
+			<< "See Documentation/sensor_driver_requirements.rst in the libcamera sources for more information";
+		return -EINVAL;
+	}
+
+	int err = 0;
+	/*
+	 * Optional controls are used to register optional sensor
+	 * properties. If not present, some values will be defaulted.
+	 */
+	const std::vector<uint32_t> optionalControls{
+		V4L2_CID_CAMERA_ORIENTATION,
+		V4L2_CID_CAMERA_SENSOR_ROTATION,
+	};
+
+	ctrls = subdev_->getControls(optionalControls);
+	if (ctrls.empty()) {
+		LOG(CameraSensor, Info)
+			<< "Optional V4L2 controls not supported";
+		err = -EINVAL;
+	}
+
+	/*
+	 * Make sure the required selection targets are supported.
+	 *
+	 * Failures in reading any of the targets are not deemed to be fatal,
+	 * but some properties and features, like constructing a
+	 * CameraSensorInfo for the IPA module, won't be supported.
+	 */
+	Rectangle rect;
+	int ret = subdev_->getSelection(pad_, V4L2_SEL_TGT_CROP_BOUNDS, &rect);
+	if (ret) {
+		LOG(CameraSensor, Info)
+			<< "Failed to retrieve the readable pixel area size";
+		err = -EINVAL;
+	}
+
+	ret = subdev_->getSelection(pad_, V4L2_SEL_TGT_CROP_DEFAULT, &rect);
+	if (ret) {
+		LOG(CameraSensor, Info)
+			<< "Failed to retrieve the active pixel area size";
+		err = -EINVAL;
+	}
+
+	ret = subdev_->getSelection(pad_, V4L2_SEL_TGT_CROP, &rect);
+	if (ret) {
+		LOG(CameraSensor, Info)
+			<< "Failed to retreive the sensor crop rectangle";
+		err = -EINVAL;
+	}
+
+	if (err) {
+		LOG(CameraSensor, Info)
+			<< "The sensor kernel driver needs to be fixed";
+		LOG(CameraSensor, Info)
+			<< "See Documentation/sensor_driver_requirements.rst in the libcamera sources for more information";
+	}
+
+	return 0;
+}
+
 int CameraSensor::initProperties()
 {
 	/*
@@ -278,21 +362,29 @@ int CameraSensor::initProperties()
 		}
 	} else {
 		propertyValue = properties::CameraLocationFront;
+		LOG(CameraSensor, Debug)
+			<< "Location property defaulted to 'Front Camera'";
 	}
 	properties_.set(properties::Location, propertyValue);
 
 	/* Camera Rotation: default is 0 degrees. */
 	const auto &rotationControl = controls.find(V4L2_CID_CAMERA_SENSOR_ROTATION);
-	if (rotationControl != controls.end())
+	if (rotationControl != controls.end()) {
 		propertyValue = rotationControl->second.def().get<int32_t>();
-	else
+	} else {
 		propertyValue = 0;
+		LOG(CameraSensor, Debug)
+			<< "Rotation property defaulted to 0 degrees";
+	}
 	properties_.set(properties::Rotation, propertyValue);
 
 	Rectangle bounds;
 	ret = subdev_->getSelection(pad_, V4L2_SEL_TGT_CROP_BOUNDS, &bounds);
 	if (!ret)
 		properties_.set(properties::PixelArraySize, bounds.size());
+	else
+		LOG(CameraSensor, Debug)
+			<< "PixelArraySize property not registered";
 
 	Rectangle crop;
 	ret = subdev_->getSelection(pad_, V4L2_SEL_TGT_CROP_DEFAULT, &crop);
@@ -306,6 +398,9 @@ int CameraSensor::initProperties()
 		crop.x -= bounds.x;
 		crop.y -= bounds.y;
 		properties_.set(properties::PixelArrayActiveAreas, { crop });
+	} else {
+		LOG(CameraSensor, Debug)
+			<< "PixelArrayActiveAreas property not registered";
 	}
 
 	/* Color filter array pattern, register only for RAW sensors. */
@@ -566,10 +661,7 @@ int CameraSensor::sensorInfo(CameraSensorInfo *info) const
 	Rectangle rect;
 	int ret = subdev_->getSelection(pad_, V4L2_SEL_TGT_CROP_DEFAULT, &rect);
 	if (ret) {
-		LOG(CameraSensor, Error)
-			<< "Failed to construct camera sensor info: "
-			<< "the camera sensor does not report the active area";
-
+		LOG(CameraSensor, Error) << "Failed to get the active area";
 		return ret;
 	}
 	info->activeAreaSize = { rect.width, rect.height };
@@ -577,9 +669,7 @@ int CameraSensor::sensorInfo(CameraSensorInfo *info) const
 	/* It's mandatory for the subdevice to report its crop rectangle. */
 	ret = subdev_->getSelection(pad_, V4L2_SEL_TGT_CROP, &info->analogCrop);
 	if (ret) {
-		LOG(CameraSensor, Error)
-			<< "Failed to construct camera sensor info: "
-			<< "the camera sensor does not report the crop rectangle";
+		LOG(CameraSensor, Error) << "Failed to get the crop rectangle";
 		return ret;
 	}
 
@@ -601,16 +691,11 @@ int CameraSensor::sensorInfo(CameraSensorInfo *info) const
 	info->bitsPerPixel = format.bitsPerPixel();
 	info->outputSize = format.size;
 
-	/*
-	 * Retrieve the pixel rate and the line length through V4L2 controls.
-	 * Support for the V4L2_CID_PIXEL_RATE and V4L2_CID_HBLANK controls is
-	 * mandatory.
-	 */
+	/* Retrieve the pixel rate and the line length through V4L2 controls. */
 	ControlList ctrls = subdev_->getControls({ V4L2_CID_PIXEL_RATE,
 						   V4L2_CID_HBLANK });
 	if (ctrls.empty()) {
-		LOG(CameraSensor, Error)
-			<< "Failed to retrieve camera info controls";
+		LOG(CameraSensor, Error) << "Failed to retrieve camera controls";
 		return -EINVAL;
 	}
 
-- 
2.29.2