[PATCH v2 1/2] libcamera: pipeline: uvcvideo: Fix `ExposureTimeMode` control setup

[Barnabás Pőcze]

`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 populated.

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

The available modes are saved for later so that the appropriate mode
can be selected when the control is set.

Fixes: bad8d591f8acfa ("libcamera: uvcvideo: Register ExposureTimeMode control")
Signed-off-by: Barnabás Pőcze <pobrn at protonmail.com>
---
 src/libcamera/pipeline/uvcvideo/uvcvideo.cpp | 46 ++++++++++++--------
 1 file changed, 27 insertions(+), 19 deletions(-)

diff --git a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
index dedcac89b..1f604b91e 100644
--- a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
@@ -6,6 +6,7 @@
  */
 
 #include <algorithm>
+#include <bitset>
 #include <cmath>
 #include <fstream>
 #include <map>
@@ -58,6 +59,13 @@ public:
 	Stream stream_;
 	std::map<PixelFormat, std::vector<SizeRange>> formats_;
 
+	std::bitset<
+		std::max(V4L2_EXPOSURE_AUTO,
+		std::max(V4L2_EXPOSURE_MANUAL,
+		std::max(V4L2_EXPOSURE_APERTURE_PRIORITY,
+			 V4L2_EXPOSURE_SHUTTER_PRIORITY))) + 1
+	> availableExposureModes_;
+
 private:
 	bool generateId();
 
@@ -725,25 +733,25 @@ 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(),
-			[&](const ControlValue &val) {
-				return (val.get<int32_t>() == V4L2_EXPOSURE_APERTURE_PRIORITY ||
-					val.get<int32_t>() == V4L2_EXPOSURE_AUTO) ? true : false;
-			});
-		if (it != v4l2Values.end())
-			values.back() = static_cast<int32_t>(controls::ExposureTimeModeAuto);
-
-		it = std::find_if(v4l2Values.begin(), v4l2Values.end(),
-			[&](const ControlValue &val) {
-				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]};
+		for (const ControlValue &value : v4l2Values) {
+			auto x = value.get<int32_t>();
+			if (0 <= x && static_cast<size_t>(x) < availableExposureModes_.size())
+				availableExposureModes_[x] = true;
+		}
+
+		std::array<ControlValue, 2> values;
+		std::size_t count = 0;
+
+		if (availableExposureModes_[V4L2_EXPOSURE_AUTO] || availableExposureModes_[V4L2_EXPOSURE_APERTURE_PRIORITY])
+			values[count++] = controls::ExposureTimeModeAuto;
+
+		if (availableExposureModes_[V4L2_EXPOSURE_MANUAL] || availableExposureModes_[V4L2_EXPOSURE_SHUTTER_PRIORITY])
+			values[count++] = controls::ExposureTimeModeManual;
+
+		if (count == 0)
+			return;
+
+		info = ControlInfo{ Span<const ControlValue>{ values.data(), count }, values[0] };
 		break;
 	}
 	case V4L2_CID_EXPOSURE_ABSOLUTE:
-- 
2.48.1