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> Since the LG UltraFine exposes a USB HID device to control its brightness, I wrote a driver to attach to it and expose the brightness adjustment through wscon

> Since the LG UltraFine exposes a USB HID device to control its brightness, I wrote a driver to attach to it and expose the brightness adjustment through wsconsctl display.brightness. Wow, that is impressive both from the device _and_ from the author. I wonder how many displays support controls over USB? Personally, I hate having to manually adjust my display's brightness in the evening. Edit: This got me curious and after digging it looks like some utilities can actually control the hardware backlight brightness, like xbacklight on linux: https://wiki.archlinux.org/title/backlight#xbacklight https://wiki.archlinux.org/title/backlight#xbacklight You can also use xrandr to control the signal brightness, but that's not really the same as controlling the hardware.

fanatic2pope 4y ago
I'm surprised more people don't know about ddc (which works over displayport). Been using it with this gnome extension on Fedora for a while now. https://github.com/daitj/gnome-display-brightness-ddcutil https://github.com/daitj/gnome-display-brightness-ddcutil
- mixmastamyk 4y ago
  I use a wrapper script around ddccontrol. Combined with backlight, I can set both monitors at once.
  - dont__panic 4y ago
    For anyone in macOS, I highly recommend MonitorControl (https://github.com/MonitorControl/MonitorControl#readme https://github.com/MonitorControl/MonitorControl#readme). No affiliation, just a happy user for nearly 2 years now.
- amendegree 4y ago
  I use display-switch which is a rust wrapper around ddcutil plus some usb-port sniffing to switch my 3 monitors between my work laptop and personal desktop. The issue is that not every monitor has full ddc support, especially consumer-targeted monitors. anything for pros will usually have pretty good support but those usually don't have great refresh rates at reasonable prices. (I noticed LG is especially bad about supporting ddc)
- jmrm 4y ago
  Not only DisplayPort. The past year I found out even works for VGA and DVI, and now I control the brightness of my monitor with the mouse wheel :-)
  - ranma42 4y ago
    DisplayPort is the more surprising one. DDC came from VGA and DVI and uses the I2C lines that also connect the EDID EEPROM, but Displayport doesn't even have I2C pins if you look at the pinout, so it has to be tunneled: "DisplayPort does not have the I2C SLA/SLC pins. Instead, the logical I2C signals are converted at each end into messages on the AUX channel. Put another way, DDC is implemented using the AUX channel, but the AUX channel itself is not DDC. The "multiplexing" of I2C over the AUX channel is transparent to all but the lowest level of I2C software at each end."

fanatic2pope 4y ago

I'm surprised more people don't know about ddc (which works over displayport). Been using it with this gnome extension on Fedora for a while now. https://github.com/daitj/gnome-display-brightness-ddcutil https://github.com/daitj/gnome-display-brightness-ddcutil

mixmastamyk 4y ago
I use a wrapper script around ddccontrol. Combined with backlight, I can set both monitors at once.
- dont__panic 4y ago
  For anyone in macOS, I highly recommend MonitorControl (https://github.com/MonitorControl/MonitorControl#readme https://github.com/MonitorControl/MonitorControl#readme). No affiliation, just a happy user for nearly 2 years now.
amendegree 4y ago
I use display-switch which is a rust wrapper around ddcutil plus some usb-port sniffing to switch my 3 monitors between my work laptop and personal desktop. The issue is that not every monitor has full ddc support, especially consumer-targeted monitors. anything for pros will usually have pretty good support but those usually don't have great refresh rates at reasonable prices. (I noticed LG is especially bad about supporting ddc)
jmrm 4y ago
Not only DisplayPort. The past year I found out even works for VGA and DVI, and now I control the brightness of my monitor with the mouse wheel :-)
- ranma42 4y ago
  DisplayPort is the more surprising one. DDC came from VGA and DVI and uses the I2C lines that also connect the EDID EEPROM, but Displayport doesn't even have I2C pins if you look at the pinout, so it has to be tunneled: "DisplayPort does not have the I2C SLA/SLC pins. Instead, the logical I2C signals are converted at each end into messages on the AUX channel. Put another way, DDC is implemented using the AUX channel, but the AUX channel itself is not DDC. The "multiplexing" of I2C over the AUX channel is transparent to all but the lowest level of I2C software at each end."