[libcamera-devel] [RFC PATCH 2/2] libcamera: camera_sensor: Do not clear camera flips when listing formats

[David Plowman]

Previously the code used to clear the camnera's h and v flip bits when
enumerating the supported formats so as to obtain any Bayer formats in
the sensor's native (untransformed) orientation. However this fails
when the camera is already in use elsewhere.

Instead, we query the current state of the flip bits and transform the
formats - which we obtain in their flipped orientation - back into
their native orientation to be stored.

Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
---
 src/libcamera/camera_sensor.cpp | 51 +++++++++++++++++++++++++++------
 1 file changed, 43 insertions(+), 8 deletions(-)

diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
index 572a313a..6670dfb9 100644
--- a/src/libcamera/camera_sensor.cpp
+++ b/src/libcamera/camera_sensor.cpp
@@ -19,6 +19,8 @@
 
 #include <libcamera/base/utils.h>
 
+#include <libcamera/transform.h>
+
 #include "libcamera/internal/bayer_format.h"
 #include "libcamera/internal/camera_lens.h"
 #include "libcamera/internal/camera_sensor_properties.h"
@@ -108,18 +110,51 @@ int CameraSensor::init()
 		return ret;
 
 	/*
-	 * Clear any flips to be sure we get the "native" Bayer order. This is
-	 * harmless for sensors where the flips don't affect the Bayer order.
+	 * We want to get the native mbus codes for the sensor, without any flips.
+	 * We can't clear any flips here, so we have to read the current values
+	 * (if the flip controls exist), decide whether they actually modify any
+	 * output Bayer pattern, and finally undo their effect on the formats.
+	 *
+	 * First, check if the flip controls exist and if so read them.
 	 */
 	ControlList ctrls(subdev_->controls());
-	if (subdev_->controls().find(V4L2_CID_HFLIP) != subdev_->controls().end())
-		ctrls.set(V4L2_CID_HFLIP, 0);
-	if (subdev_->controls().find(V4L2_CID_VFLIP) != subdev_->controls().end())
-		ctrls.set(V4L2_CID_VFLIP, 0);
-	subdev_->setControls(&ctrls);
+	std::vector<uint32_t> flipCtrlIds;
+	bool hasHflip = subdev_->controls().find(V4L2_CID_HFLIP) != subdev_->controls().end();
+	bool hasVflip = subdev_->controls().find(V4L2_CID_VFLIP) != subdev_->controls().end();
+	if (hasHflip)
+		flipCtrlIds.push_back(V4L2_CID_HFLIP);
+	if (hasVflip)
+		flipCtrlIds.push_back(V4L2_CID_VFLIP);
+	ControlList flipCtrls = subdev_->getControls(flipCtrlIds);
+
+	/* Now construct a transform that would undo any flips. */
+	Transform transform = Transform::Identity;
+	if (hasHflip && flipCtrls.get(V4L2_CID_HFLIP).get<int>()) {
+		const struct v4l2_query_ext_ctrl *extCtrl = subdev_->controlInfo(V4L2_CID_HFLIP);
+		if (extCtrl->flags & V4L2_CTRL_FLAG_MODIFY_LAYOUT)
+			transform |= Transform::HFlip;
+	}
+	if (hasVflip && flipCtrls.get(V4L2_CID_VFLIP).get<int>()) {
+		const struct v4l2_query_ext_ctrl *extCtrl = subdev_->controlInfo(V4L2_CID_VFLIP);
+		if (extCtrl->flags & V4L2_CTRL_FLAG_MODIFY_LAYOUT)
+			transform |= Transform::VFlip;
+	}
+
+	/* Finally get the formats, and apply the transform to the mbus codes. */
+	auto formats = subdev_->formats(pad_);
+	for (const auto &format : formats) {
+		unsigned int mbusCode = format.first;
+		BayerFormat bayerFormat = BayerFormat::fromMbusCode(mbusCode);
+		bool valid = true;
+
+		if (bayerFormat.isValid())
+			mbusCode = bayerFormat.transform(transform).toMbusCode(valid);
+
+		if (valid)
+			formats_[mbusCode] = std::move(format.second);
+	}
 
 	/* Enumerate, sort and cache media bus codes and sizes. */
-	formats_ = subdev_->formats(pad_);
 	if (formats_.empty()) {
 		LOG(CameraSensor, Error) << "No image format found";
 		return -EINVAL;
-- 
2.30.2