[libcamera-devel] [PATCH] libcamera: camera_sensor: fix HBLANK RO check

[Alain Volmat]

Perform the HBLANK readonly check by looking at the v4l2_query_ext_ctrl
struct for the V4L2_CID_HBLANK instead of checking for min/max values.

Signed-off-by: Alain Volmat <alain.volmat at foss.st.com>
---
 src/libcamera/camera_sensor.cpp | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
index 0ef78d9c..3281c1f9 100644
--- a/src/libcamera/camera_sensor.cpp
+++ b/src/libcamera/camera_sensor.cpp
@@ -188,21 +188,12 @@ int CameraSensor::init()
 	 * 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.
 	 */
 	if (ctrls.infoMap()->find(V4L2_CID_HBLANK) != ctrls.infoMap()->end()) {
-		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) {
+		const struct v4l2_query_ext_ctrl *hblankInfo = subdev_->controlInfo(V4L2_CID_HBLANK);
+		if (!(hblankInfo->flags & V4L2_CTRL_FLAG_READ_ONLY)) {
+			const ControlInfo hblank = ctrls.infoMap()->at(V4L2_CID_HBLANK);
+			const int32_t hblankMin = hblank.min().get<int32_t>();
 			ControlList ctrl(subdev_->controls());
 
 			ctrl.set(V4L2_CID_HBLANK, hblankMin);
-- 
2.25.1