DonaldKellett/90-logitech-c930e.rules

## 90-logitech-c930e.rules
KERNEL=="video[0-9]*", SUBSYSTEM=="video4linux", ATTRS{idVendor}=="046d", ATTRS{idProduct}=="0843", TAG+="systemd", ENV{SYSTEMD_WANTS}="logitech-c930e@$env{MINOR}.service"

## README.md

      
    Raw
  

              README.md
            
          
    Logitech c930e initialization rule

The Logitech c930e has autofocus enabled by default, which fails to focus on objects close to the camera after relaxing the focus to distant objects. This is usually not much of a problem in video meetings, but for use cases such as online proctored exams where the invigilator requests an identity document to be presented close to the camera, this lack of focus can render the text on the identity document unreadable, making the camera useless for such exams.
This gist corrects the issue by disabling autofocus and manually setting the focus so that close-up text can be seen clearly, yet distant objects do not appear too blurry.
This solution has been tested on Fedora 35 Workstation, though it can probably be used on many other Linux distributions as well with minimal modification. In particular, for Ubuntu 20.04, replace focus_automatic_continuous with focus_auto.
Prerequisites

Ensure the v4l-utils package is installed.
Usage


Place the file 90-logitech-c930e.rules under /etc/udev/rules.d


Place the file logitech-c930e@.service under /etc/systemd/system


Place the file logitech-c930e.sh under /root and mark it executable


Restart systemd-udevd.service and reload systemd:
$ sudo systemctl restart systemd-udevd.service
$ sudo systemctl daemon-reload


Unplug and re-plug your Logitech c930e webcam. The rules should now be effective. Enjoy ;-)


References


Webcam setup - ArchWiki: https://wiki.archlinux.org/title/webcam_setup
yookoala/90-mac-superdrive.rules: https://gist.github.com/yookoala/818c1ff057e3d965980b7fd3bf8f77a6
Long-running systemd service with udev: http://blog.fraggod.net/2012/06/16/proper-ish-way-to-start-long-running-systemd-service-on-udev-event-device-hotplug.html

Related questions


Ask Ubuntu: https://askubuntu.com/questions/1393244/logitech-c930e-focus-reverts-to-default-settings-even-with-custom-udev-rules
Ask Fedora: https://ask.fedoraproject.org/t/logitech-c930e-focus-reverts-to-default-settings-even-with-custom-udev-rules/20209

License

CC0 (public domain)

  
## logitech-c930e.sh
#!/bin/bash

if [[ $# -ne 1 ]]; then
  echo "Expected minor device number as sole argument" 1>&2
  exit 1
fi

while true; do
  v4l2-ctl -d $1 --set-ctrl focus_automatic_continuous=0
  v4l2-ctl -d $1 --set-ctrl focus_absolute=75
  sleep 5
done

## logitech-c930e@.service
[Unit]
Description=Disable autofocus and set absolute focus for Logitech c930e

[Service]
ExecStart=/bin/bash -c "/root/logitech-c930e.sh %I"

[Install]
WantedBy=multi-user.target
	#!/bin/bash

	if [[ $# -ne 1 ]]; then
	echo "Expected minor device number as sole argument" 1>&2
	exit 1
	fi

	while true; do
	v4l2-ctl -d $1 --set-ctrl focus_automatic_continuous=0
	v4l2-ctl -d $1 --set-ctrl focus_absolute=75
	sleep 5
	done
	[Unit]
	Description=Disable autofocus and set absolute focus for Logitech c930e

	[Service]
	ExecStart=/bin/bash -c "/root/logitech-c930e.sh %I"

	[Install]
	WantedBy=multi-user.target