DDC alt mode USB-C input not working on LG UltraWide Monitor 34U650A-B

[mikecarlton]

The LG UltraWide Monitor 34U650A-B is a relatively new monitor from LG.

The input selection codes for HDMI-1 (144), HDMI-2 (145) and Display Port 1 (208) all seem to work correctly.
However the listed USB-C input selection code 210 does not work (there is no response)

Via exhaustive search (a bash one-liner), I found the code 465 works for my monitor. The following example will select USB-C input:

betterdisplaycli set --namelike=ultrawide --ddcAlt --vcp=inputSelectAlt --value=465

Maybe you can add that to documentation or defaults somewhere?

Thanks for the efforts, this is a very useful project

[TheoLyn69]

Hello @mikecarlton (maybe @waydabber, but it's mainly a question and probably not an issue...)

Sorry for disturbing you, but I've just bought this LG monitor, but I have a strange issue and it might be the same you wrote a few weeks ago... but not sure.

I plugged the monitor to my dock station (REVODOK), which is plugged to my macbook pro using thunderbolt cable.
When macOS sleeps, monitor stands by. But waking up macOS, monitor goes on with a full HD resolution by default (and macOS doesn't let me to choose a 3440x1440 resolution).
I installed betterdisplay as it might be a solution, but nothing works. Is it the same problem as yours ? if yes, can you explain a little bit what you did to solve it ? Not very betterdisplay-qualified as I installed it yesterday and seems to be a very "technical" thing...

Help will be really appreciated. If you can't/don't want to answer, no problem. I will keep on searching solving my issue.

--
Sylvain

[mikecarlton]

I have my monitor plugged directly into laptop (16" MacBook Pro with M1) via USB-C.
I have no issues with resolution, I run it exclusively in 3440x1440.

I would suggest plugging the monitor directly into the MacBook to see if the dock is the source of the issue. I don't use a dock, so don't have any more info, sorry.

[TheoLyn69]

Thank you for your reply @mikecarlton
I'm pretty sure the dock is the source of the issue (note: chatGPT seems to have confirmed), but plugging 2 cables into my laptop (I switch between a macOS one - personal - and a Windows one - work) would not be very handy.
I keep on trying to find a way to force this screen to be in an ultrawide resolution after waking up from mac...

Thanks, and have a nice day !

Sylvain

[waydabber]

I'll move this to discussions as it is not clear whether this is an app issue or anything that can be fixed. But of course if it turns out to be a bug, we'll revisit the problem.