[libcamera-devel,v6,7/9] libcamera: pipeline: uvcvideo: Generate unique camera names

Message ID 20200803211733.1037019-8-niklas.soderlund@ragnatech.se
State Superseded
Headers show
Series
  • libcamera: Generate unique and stable camera IDs
Related show

Commit Message

Niklas Söderlund Aug. 3, 2020, 9:17 p.m. UTC
Generate camera names that are unique and persistent between system
resets. The name is constructed from the USB device information as well
as the USB controller on the host.

Before this change example of camera names:

Venus USB2.0 Camera: Venus USB2
Logitech Webcam C930e

After this change the same cameras are:

\_SB_.PCI0.RP05.PXSX-2.1.1:1.0-0ac8:3420
\_SB_.PCI0.RP05.PXSX-2.4:1.0-046d:0843

On OF-based system:

base/soc/usb@7e980000/usb-port@1-1.3:1.0-0ac8:3420

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
---
* Changes since v5
- New algorithm to generate IDs.

* Changes since v3
- Switch argument to generateName() to UVCCameraData pointer.
---
 src/libcamera/pipeline/uvcvideo/uvcvideo.cpp | 76 +++++++++++++++++++-
 1 file changed, 75 insertions(+), 1 deletion(-)

Patch

diff --git a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
index 93e3dc17e3a7105e..6a997bb5937a4a9c 100644
--- a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
@@ -6,6 +6,7 @@ 
  */
 
 #include <algorithm>
+#include <fstream>
 #include <iomanip>
 #include <math.h>
 #include <tuple>
@@ -81,6 +82,8 @@  public:
 	bool match(DeviceEnumerator *enumerator) override;
 
 private:
+	std::string generateID(const UVCCameraData *data);
+
 	int processControl(ControlList *controls, unsigned int id,
 			   const ControlValue &value);
 	int processControls(UVCCameraData *data, Request *request);
@@ -379,6 +382,71 @@  int PipelineHandlerUVC::queueRequestDevice(Camera *camera, Request *request)
 	return 0;
 }
 
+std::string PipelineHandlerUVC::generateID(const UVCCameraData *data)
+{
+	const std::string path = data->video_->devicePath();
+
+	/* Creata a device ID from the USB devices vendor and product ID. */
+	std::string deviceId;
+	for (const std::string &name : { "idVendor", "idProduct" }) {
+		std::ifstream file(path + "/../" + name);
+
+		if (!file.is_open())
+			return {};
+
+		std::string value;
+		std::getline(file, value);
+		file.close();
+
+		deviceId += value + (deviceId.empty() ? ":" : "");
+	}
+
+	/*
+	 * Create a USB ID from the device path which has the known format:
+	 *
+	 *	bus , "-", ports, ":", config, ".", interface ;
+	 *	bus = number ;
+	 *	ports = port, [ ".", ports ] ;
+	 *	port = number ;
+	 *	config = number ;
+	 *	interface = number ;
+	 *
+	 * Example: 3-2.4:1.0
+	 *
+	 * The bus is not guaranteed to be stable and needs to be stripped from
+	 * the USB ID. The final USB ID is built up of the ports, config and
+	 * interface properties.
+	 *
+	 * Example 2.4:1.0.
+	 */
+	std::string usbId = basename(path.c_str());
+	usbId = usbId.substr(usbId.find('-') + 1, std::string::npos);
+
+	/* Create a controller ID from first device described in firmware. */
+	std::string controllerId;
+	std::string searchPath = path;
+	while (true) {
+		searchPath += "/..";
+		char *realPath = realpath(searchPath.c_str(), nullptr);
+		if (!realPath) {
+			LOG(UVC, Error) << "Failed to lookup " << searchPath;
+			return {};
+		}
+		searchPath = realPath;
+		free(realPath);
+
+		if (searchPath.empty() || searchPath == "/") {
+			LOG(UVC, Error) << "Can not find controller ID";
+			return {};
+		}
+
+		if (!utils::tryLookupFirmwareID(searchPath, &controllerId))
+			break;
+	}
+
+	return controllerId + "-" + usbId + "-" + deviceId;
+}
+
 bool PipelineHandlerUVC::match(DeviceEnumerator *enumerator)
 {
 	MediaDevice *media;
@@ -405,8 +473,14 @@  bool PipelineHandlerUVC::match(DeviceEnumerator *enumerator)
 		return false;
 
 	/* Create and register the camera. */
+	std::string id = generateID(data.get());
+	if (id.empty()) {
+		LOG(UVC, Error) << "Failed to generate camera ID";
+		return false;
+	}
+
 	std::set<Stream *> streams{ &data->stream_ };
-	std::shared_ptr<Camera> camera = Camera::create(this, media->model(), streams);
+	std::shared_ptr<Camera> camera = Camera::create(this, id, streams);
 	registerCamera(std::move(camera), std::move(data));
 
 	/* Enable hot-unplug notifications. */