I use a USB host-side switch [0] to quickly move my keyboard and mouse between my desktop and my laptop's docking station, since my 4k monitor already supports multiple inputs, and 4k capable KVMs are expensive and buggy.
In order to make the switch, I push one button on the USB switch, and then select the next input on my monitor (four button presses using the monitor's OSD). There's a great little tool called ddcutil [1] that allows you to send commands to your monitor via the i2c bus embedded in your HDMI/DisplayPort connection, so I tried to write a script to do the monitor input swap on either a key binding or after detecting the appropriate USB event.
It almost worked. My monitor only listens to the i2c bus of the selected input, so I need to run this script on both my desktop and laptop rather than just on the desktop. But apparently there was a bug in the way my (TB3) dock handled forwarding of the DP i2c data to the docking host. And by bug, I mean write forwarding was just not implemented in the kernel driver. So ddcutil would work on my laptop with a direct HDMI connection, but not when it was connected via the dock.
Anyway, long story short:
5.10 fixes this [2], so I'm particularly excited about this release.
[0] https://www.amazon.com/Cable-Matters-Sharing-Computers-Perip...
[1] https://github.com/rockowitz/ddcutil
[2] https://lkml.org/lkml/2020/9/1/300
In order to make the switch, I push one button on the USB switch, and then select the next input on my monitor (four button presses using the monitor's OSD). There's a great little tool called ddcutil [1] that allows you to send commands to your monitor via the i2c bus embedded in your HDMI/DisplayPort connection, so I tried to write a script to do the monitor input swap on either a key binding or after detecting the appropriate USB event.
It almost worked. My monitor only listens to the i2c bus of the selected input, so I need to run this script on both my desktop and laptop rather than just on the desktop. But apparently there was a bug in the way my (TB3) dock handled forwarding of the DP i2c data to the docking host. And by bug, I mean write forwarding was just not implemented in the kernel driver. So ddcutil would work on my laptop with a direct HDMI connection, but not when it was connected via the dock.
Anyway, long story short:
5.10 fixes this [2], so I'm particularly excited about this release.
[0] https://www.amazon.com/Cable-Matters-Sharing-Computers-Perip...
[1] https://github.com/rockowitz/ddcutil
[2] https://lkml.org/lkml/2020/9/1/300