[libcamera-devel] [PATCH v2 1/1] libcamera: camera_sensor: Reset HBLANK when setting the format

[David Plowman]

We no longer reset the HBLANK in init because we may not own the
camera and the operation may fail. Instead, we reset it when we set
the camera format so that all pipeline handlers, even ones that do not
control HBLANK themselves, will have a well-defined value.

Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
---
 src/libcamera/camera_sensor.cpp | 53 ++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 27 deletions(-)

diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
index 572a313a..ec7bb0e7 100644
--- a/src/libcamera/camera_sensor.cpp
+++ b/src/libcamera/camera_sensor.cpp
@@ -176,32 +176,6 @@ 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);
 }
 
@@ -748,7 +722,32 @@ int CameraSensor::setFormat(V4L2SubdeviceFormat *format)
 		return ret;
 
 	updateControlInfo();
-	return 0;
+
+	/*
+	 * 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 = controls().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);
+	}
+
+	return ret;
 }
 
 /**
-- 
2.30.2