camera_sensor: Add minimum and maximum line length to IPACameraSensorInfo

Add fields for minimum and maximum line length (in units of pixels) to
the IPACameraSensorInfo structure. This replaces the existing lineLength
field.

Update the ipu3, raspberrypi and rkisp1 IPAs to use
IPACameraSensorInfo::minLineLength instead of
IPACameraSensorInfo::lineLength, as logically we will always want to use
the fastest sensor readout by default.

Since the IPAs now use minLineLength for their calculations, set the
starting value of the V4L2_CID_HBLANK control to its minimum in
CameraSensor::init().

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Tested-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

4 files changed, 36 insertions, 6 deletions

diff --git a/src/ipa/ipu3/ipu3.cpp b/src/ipa/ipu3/ipu3.cpp
index 852deb71..891643e0 100644
--- a/src/ipa/ipu3/ipu3.cpp
+++ b/src/ipa/ipu3/ipu3.cpp
@@ -336,7 +336,8 @@ int IPAIPU3::init(const IPASettings &settings,
 
 	/* Clean context */
 	context_.configuration = {};
-	context_.configuration.sensor.lineDuration = sensorInfo.lineLength * 1.0s / sensorInfo.pixelRate;
+	context_.configuration.sensor.lineDuration = sensorInfo.minLineLength
+						   * 1.0s / sensorInfo.pixelRate;
 
 	/* Load the tuning data file. */
 	File file(settings.configurationFile);
@@ -499,7 +500,8 @@ int IPAIPU3::configure(const IPAConfigInfo &configInfo,
 	context_.frameContexts.clear();
 
 	/* Initialise the sensor configuration. */
-	context_.configuration.sensor.lineDuration = sensorInfo_.lineLength * 1.0s / sensorInfo_.pixelRate;
+	context_.configuration.sensor.lineDuration = sensorInfo_.minLineLength
+						   * 1.0s / sensorInfo_.pixelRate;
 
 	/*
 	 * Compute the sensor V4L2 controls to be used by the algorithms and
diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp
index 14b06a4f..ec495a37 100644
--- a/src/ipa/raspberrypi/raspberrypi.cpp
+++ b/src/ipa/raspberrypi/raspberrypi.cpp
@@ -356,7 +356,7 @@ void IPARPi::setMode(const IPACameraSensorInfo &sensorInfo)
 	 * Calculate the line length as the ratio between the line length in
 	 * pixels and the pixel rate.
 	 */
-	mode_.lineLength = sensorInfo.lineLength * (1.0s / sensorInfo.pixelRate);
+	mode_.lineLength = sensorInfo.minLineLength * (1.0s / sensorInfo.pixelRate);
 
 	/*
 	 * Set the frame length limits for the mode to ensure exposure and
diff --git a/src/ipa/rkisp1/rkisp1.cpp b/src/ipa/rkisp1/rkisp1.cpp
index 022595f3..3f5c1a58 100644
--- a/src/ipa/rkisp1/rkisp1.cpp
+++ b/src/ipa/rkisp1/rkisp1.cpp
@@ -246,7 +246,7 @@ int IPARkISP1::configure([[maybe_unused]] const IPACameraSensorInfo &info,
 	context_.configuration.hw.revision = hwRevision_;
 
 	context_.configuration.sensor.size = info.outputSize;
-	context_.configuration.sensor.lineDuration = info.lineLength * 1.0s / info.pixelRate;
+	context_.configuration.sensor.lineDuration = info.minLineLength * 1.0s / info.pixelRate;
 
 	/*
 	 * When the AGC computes the new exposure values for a frame, it needs
diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
index 911fd0be..572a313a 100644
--- a/src/libcamera/camera_sensor.cpp
+++ b/src/libcamera/camera_sensor.cpp
@@ -176,6 +176,32 @@ int CameraSensor::init()
 	if (ret)
 		return ret;
 
+	/*
+	 * Set HBLANK to the minimum to start with a well-defined line length,
+	 * allowing IPA modules that do not modify HBLANK to use the sensor
+	 * minimum line length in their calculations.
+	 *
+	 * At present, there is no way of knowing if a control is read-only.
+	 * As a workaround, assume that if the minimum and maximum values of
+	 * the V4L2_CID_HBLANK control are the same, it implies the control
+	 * is read-only.
+	 *
+	 * \todo The control API ought to have a flag to specify if a control
+	 * is read-only which could be used below.
+	 */
+	const ControlInfo hblank = ctrls.infoMap()->at(V4L2_CID_HBLANK);
+	const int32_t hblankMin = hblank.min().get<int32_t>();
+	const int32_t hblankMax = hblank.max().get<int32_t>();
+
+	if (hblankMin != hblankMax) {
+		ControlList ctrl(subdev_->controls());
+
+		ctrl.set(V4L2_CID_HBLANK, hblankMin);
+		ret = subdev_->setControls(&ctrl);
+		if (ret)
+			return ret;
+	}
+
 	return applyTestPatternMode(controls::draft::TestPatternModeEnum::TestPatternModeOff);
 }
 
@@ -883,10 +909,12 @@ int CameraSensor::sensorInfo(IPACameraSensorInfo *info) const
 		return -EINVAL;
 	}
 
-	int32_t hblank = ctrls.get(V4L2_CID_HBLANK).get<int32_t>();
-	info->lineLength = info->outputSize.width + hblank;
 	info->pixelRate = ctrls.get(V4L2_CID_PIXEL_RATE).get<int64_t>();
 
+	const ControlInfo hblank = ctrls.infoMap()->at(V4L2_CID_HBLANK);
+	info->minLineLength = info->outputSize.width + hblank.min().get<int32_t>();
+	info->maxLineLength = info->outputSize.width + hblank.max().get<int32_t>();
+
 	const ControlInfo vblank = ctrls.infoMap()->at(V4L2_CID_VBLANK);
 	info->minFrameLength = info->outputSize.height + vblank.min().get<int32_t>();
 	info->maxFrameLength = info->outputSize.height + vblank.max().get<int32_t>();