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-rw-r--r--src/v4l2/v4l2_compat_manager.cpp32
1 files changed, 27 insertions, 5 deletions
diff --git a/src/v4l2/v4l2_compat_manager.cpp b/src/v4l2/v4l2_compat_manager.cpp
index 0f7575c5..5e8cdb4f 100644
--- a/src/v4l2/v4l2_compat_manager.cpp
+++ b/src/v4l2/v4l2_compat_manager.cpp
@@ -24,6 +24,7 @@
#include <libcamera/camera.h>
#include <libcamera/camera_manager.h>
+#include <libcamera/property_ids.h>
#include "v4l2_camera_file.h"
@@ -113,14 +114,35 @@ int V4L2CompatManager::getCameraIndex(int fd)
if (ret < 0)
return -1;
- std::shared_ptr<Camera> target = cm_->get(statbuf.st_rdev);
- if (!target)
- return -1;
+ const dev_t devnum = statbuf.st_rdev;
+ /*
+ * Iterate each known camera and identify if it reports this nodes
+ * device number in its list of SystemDevices.
+ */
auto cameras = cm_->cameras();
for (auto [index, camera] : utils::enumerate(cameras)) {
- if (camera == target)
- return index;
+ Span<const int64_t> devices = camera->properties()
+ .get(properties::SystemDevices)
+ .value_or(Span<int64_t>{});
+
+ /*
+ * While there may be multiple cameras that could reference the
+ * same device node, we take a first match as a best effort for
+ * now.
+ *
+ * \todo Each camera can be accessed through any of the video
+ * device nodes that it uses. This may confuse applications.
+ * Consider reworking the V4L2 adaptation layer to instead
+ * expose each Camera instance through a single video device
+ * node (with a consistent and stable mapping). The other
+ * device nodes could possibly be hidden from the application
+ * by intercepting additional calls to the C library.
+ */
+ for (const int64_t dev : devices) {
+ if (dev == static_cast<int64_t>(devnum))
+ return index;
+ }
}
return -1;