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v4l2: Use SystemDevices properties to identify cameras

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The CameraManager->get(dev_t) helper was implemented only to support the
V4L2 Adaptation layer, and has been deprecated now that a new camera
property - SystemDevices has been introduced.

Rework the implementation of getCameraIndex() to use the SystemDevices
property and remove reliance on the now deprecated call.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
This commit is contained in:
Kieran Bingham 2023-07-04 23:57:45 +01:00
parent f7a9f14156
commit bff6d95281
1 changed files with 27 additions and 5 deletions
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32
src/v4l2/v4l2_compat_manager.cpp
View file

@ -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;