[libcamera-devel] [PATCH 0/9] libcamera: camera: Add camera ID

[Niklas Söderlund]

Hello,

This series aims to add a ID to each camera in addition to it's more 
user-friendly name. The ID is unique and persistent between reboots of 
the same system. The use-case for this is to create a single 
machine-friendly ID that can be stored and used to always resolve to the 
same camera.

The idea on how to generate a ID is to take the sysfs path of the sensor 
device which is part of each camera pipeline. As the path describes the 
location of the sensor hardware it is persistent across reboots and as 
the path is read from sysfs it's guaranteed to be unique in the system.

For pipelines that do not have a sensor (UVC) the sysfs path of the main 
video device is used instead. That path resolves to the USB device and 
includes the USB bus information so it satisfy the ID requirements.

While working with this problem it became apparent that two pipelines 
diverge from the others on how they name their cameras, raspberrypi and 
vimc. This series aligns these two and adds a helper to avoid such 
situations in the future. Unfortunately this means the user-friendly 
name of the sensor changes but this proves the need for a 
machine-friendly ID which luckily this series also adds :-)

Before this series camera user-friendly names on different systems 
looked like this (I do not have access to a simple pipeline device):

- ipu3
        ov13858 8-0010
        ov5670 10-0036
- raspberrypi
        imx219
- rkisp1
        ov5695 7-0036
        ov2685 7-003c
- uvcvideo
        Logitech Webcam C930e
- vimc
        VIMC Sensor B

With this series applied the user-friendly names machine-friendly ID on 
the same systems look like this:

The format is:
    <user-friendly name> (<machine-friendly ID>)

- ipu3
        ov13858 8-0010 (pci0000:00/0000:00:15.2/i2c_designware.2/i2c-8/i2c-OVTID858:00)
        ov5670 10-0036 (pci0000:00/0000:00:19.2/i2c_designware.5/i2c-10/i2c-INT3479:00)
- raspberrypi
        imx219 10-0010 (platform/soc/3f205000.i2c/i2c-11/i2c-10/10-0010)
- rkisp1
        ov5695 7-0036 (platform/ff160000.i2c/i2c-7/7-0036)
        ov2685 7-003c (platform/ff160000.i2c/i2c-7/7-003c)
- uvcvideo
        Logitech Webcam C930e (pci0000:00/0000:00:1c.4/0000:08:00.0/0000:09:02.0/0000:25:00.0/usb3/3-2/3-2.4/3-2.4:1.0)
- vimc
        Sensor B (platform/vimc.0)

Where it previously where possible to select a camera by its 
user-friendly name its now possible to also select it using its 
machine-friendly one. The following is therefor two equivalent 
commands:

    $ cam -c "Logitech Webcam C930e" -C
    $ cam -c "pci0000:00/0000:00:1c.4/0000:08:00.0/0000:09:02.0/0000:25:00.0/usb3/3-2/3-2.4/3-2.4:1.0" -C

Niklas Söderlund (9):
  libcamera: v4l2_device: Add method to lookup device path
  libcamera: camera_sensor: Expose a sensor ID
  libcamera: camera: Add camera ID
  libcamera: camera_manager: Enforce unique camera IDs
  libcamera: camera_manager: Try to match camera IDs first
  libcamera: pipeline: vimc: Align camera name
  libcamera: pipeline: raspberrypi: Align camera name
  libcamera: camera: Add create() that operates on CameraSensor
  cam: Print camera IDs when listing cameras

 include/libcamera/camera.h                    | 11 +++-
 include/libcamera/internal/camera_sensor.h    |  2 +
 include/libcamera/internal/v4l2_device.h      |  1 +
 src/cam/main.cpp                              |  3 +-
 src/libcamera/camera.cpp                      | 54 +++++++++++++++----
 src/libcamera/camera_manager.cpp              | 13 +++++
 src/libcamera/camera_sensor.cpp               | 17 ++++++
 src/libcamera/pipeline/ipu3/ipu3.cpp          |  9 ++--
 .../pipeline/raspberrypi/raspberrypi.cpp      |  3 +-
 src/libcamera/pipeline/rkisp1/rkisp1.cpp      |  2 +-
 src/libcamera/pipeline/simple/simple.cpp      |  3 +-
 src/libcamera/pipeline/uvcvideo/uvcvideo.cpp  |  7 ++-
 src/libcamera/pipeline/vimc/vimc.cpp          |  4 +-
 src/libcamera/v4l2_device.cpp                 | 27 ++++++++++
 test/camera/buffer_import.cpp                 |  2 +-
 test/camera/capture.cpp                       |  2 +-
 test/camera/configuration_default.cpp         |  2 +-
 test/camera/configuration_set.cpp             |  2 +-
 test/camera/statemachine.cpp                  |  2 +-
 test/controls/control_info_map.cpp            |  2 +-
 test/controls/control_list.cpp                |  2 +-
 21 files changed, 138 insertions(+), 32 deletions(-)

-- 
2.27.0