libcamera: pipeline: uvcvideo: Fix ExposureTimeMode control setup

`ControlInfo(Span<const int32_t>{...})` calls the incorrect constructor
of `ControlInfo`. The intended constructor to be called is
`ControlInfo(Span<const ControlValue>, ...)` however that is not called
because a span of `const int32_t` is passed. Instead, the constructor
`ControlInfo(const ControlValue &min, const ControlValue &max, ...)`
will be called.

Furthermore, since `values.back()` is used, only the last element of
the array is actually set.

To fix this, convert the array to contain `ControlValue` objects and use
a separate variable to keep track of which element to set next.

For each of `ExposureTimeMode{Auto,Manual}` save the V4L2 control value
that is to be used when the libcamera control is set.

Fixes: bad8d591f8 ("libcamera: uvcvideo: Register ExposureTimeMode control")
Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>

src/libcamera/pipeline/uvcvideo/uvcvideo.cpp

@@ -6,10 +6,12 @@
  */
 
 #include <algorithm>
+#include <bitset>
 #include <cmath>
 #include <fstream>
 #include <map>
 #include <memory>
+#include <optional>
 #include <set>
 #include <string>
 #include <vector>
@@ -56,6 +58,9 @@ public:
 	Stream stream_;
 	std::map<PixelFormat, std::vector<SizeRange>> formats_;
 
+	std::optional<v4l2_exposure_auto_type> autoExposureMode_;
+	std::optional<v4l2_exposure_auto_type> manualExposureMode_;
+
 private:
 	bool generateId();
 
@@ -106,6 +111,26 @@ private:
 	}
 };
 
+namespace {
+
+std::optional<controls::ExposureTimeModeEnum> v4l2ToExposureMode(int32_t x)
+{
+	using namespace controls;
+
+	switch (x) {
+	case V4L2_EXPOSURE_AUTO:
+	case V4L2_EXPOSURE_APERTURE_PRIORITY:
+		return ExposureTimeModeAuto;
+	case V4L2_EXPOSURE_MANUAL:
+	case V4L2_EXPOSURE_SHUTTER_PRIORITY:
+		return ExposureTimeModeManual;
+	default:
+		return {};
+	}
+}
+
+} /* namespace */
+
 UVCCameraConfiguration::UVCCameraConfiguration(UVCCameraData *data)
 	: CameraConfiguration(), data_(data)
 {
@@ -723,25 +748,52 @@ void UVCCameraData::addControl(uint32_t cid, const ControlInfo &v4l2Info,
 		 * ExposureTimeModeManual = { V4L2_EXPOSURE_MANUAL,
 		 *			      V4L2_EXPOSURE_SHUTTER_PRIORITY }
 		 */
-		std::array<int32_t, 2> values{};
 
-		auto it = std::find_if(v4l2Values.begin(), v4l2Values.end(),
+		std::bitset<
-			[&](const ControlValue &val) {
+			std::max(V4L2_EXPOSURE_AUTO,
-				return (val.get<int32_t>() == V4L2_EXPOSURE_APERTURE_PRIORITY ||
+			std::max(V4L2_EXPOSURE_APERTURE_PRIORITY,
-					val.get<int32_t>() == V4L2_EXPOSURE_AUTO) ? true : false;
+			std::max(V4L2_EXPOSURE_MANUAL,
-			});
+				 V4L2_EXPOSURE_SHUTTER_PRIORITY))) + 1
-		if (it != v4l2Values.end())
+		> exposureModes;
-			values.back() = static_cast<int32_t>(controls::ExposureTimeModeAuto);
+		std::optional<controls::ExposureTimeModeEnum> lcDef;
 
-		it = std::find_if(v4l2Values.begin(), v4l2Values.end(),
+		for (const ControlValue &value : v4l2Values) {
-			[&](const ControlValue &val) {
+			const auto x = value.get<int32_t>();
-				return (val.get<int32_t>() == V4L2_EXPOSURE_SHUTTER_PRIORITY ||
-					val.get<int32_t>() == V4L2_EXPOSURE_MANUAL) ? true : false;
-			});
-		if (it != v4l2Values.end())
-			values.back() = static_cast<int32_t>(controls::ExposureTimeModeManual);
 
-		info = ControlInfo{Span<int32_t>{values}, values[0]};
+			if (0 <= x && static_cast<std::size_t>(x) < exposureModes.size()) {
+				exposureModes[x] = true;
+
+				if (x == def)
+					lcDef = v4l2ToExposureMode(x);
+			}
+		}
+
+		if (exposureModes[V4L2_EXPOSURE_AUTO])
+			autoExposureMode_ = V4L2_EXPOSURE_AUTO;
+		else if (exposureModes[V4L2_EXPOSURE_APERTURE_PRIORITY])
+			autoExposureMode_ = V4L2_EXPOSURE_APERTURE_PRIORITY;
+
+		if (exposureModes[V4L2_EXPOSURE_SHUTTER_PRIORITY])
+			manualExposureMode_ = V4L2_EXPOSURE_SHUTTER_PRIORITY;
+		else if (exposureModes[V4L2_EXPOSURE_MANUAL])
+			manualExposureMode_ = V4L2_EXPOSURE_MANUAL;
+
+		std::array<ControlValue, 2> values;
+		std::size_t count = 0;
+
+		if (autoExposureMode_)
+			values[count++] = controls::ExposureTimeModeAuto;
+
+		if (manualExposureMode_)
+			values[count++] = controls::ExposureTimeModeManual;
+
+		if (count == 0)
+			return;
+
+		info = ControlInfo{
+			Span<const ControlValue>{ values.data(), count },
+			!lcDef ? values.front() : *lcDef,
+		};
 		break;
 	}
 	case V4L2_CID_EXPOSURE_ABSOLUTE: