display-switch: Failed to get current input

Monitor: Dell U2415 connected to my Macbook Pro 15 2017 via a mini display port -> usb-c adapter

When I launch display-switch, it immediately prints the following lines:

18:02:42 [ERROR] Failed to get current input for display '0'
18:02:42 [ERROR] Failed to get current input for display '1'

See Update Below It’s also not clear to me which monitor_input value I should use for mini display port (I’ve tried them all, but none of them work, I get 18:02:46 [ERROR] Failed to set display '1' to 0xf), but I don’t think it currently matters since it can’t seem to talk to my monitor. I know this monitor supports DDC/CI because I created some shortcuts in windows using dell display manager and can switch the inputs from there, so maybe it’s the dongle getting in the way?

I have a mini-dp to display port adapter coming soon that I’m going to plug into the dock I have connected to the mbp, so I’ll give it a shot once that gets here and see how I fare, but if you have any advice I’d appreciate it! Love the idea!

Update: I was able to use ddcctl to verify that that works (and I will use DisplayPort2 to switch to mini display port). So not sure why display-switch can’t read the current monitor input, maybe because of the dongle?

Update 2: Removing the dongle and going from my dock to the monitor via DisplayPort didn’t solve the problem either 😦

About this issue

Original URL
State: closed
Created 4 years ago
Comments: 15 (6 by maintainers)

Most upvoted comments

Thanks for the logs. I’m working on rewriting the DDC/CI code on macOS specifically, the library I used does not work reliably enough. I’ll post a link to a branch here for testing, once I have something working.

haimgel on Sep 17, 2020

Interesting, display-switch doesn’t successfully switch inputs for me, this is what I see:

21:36:40 [INFO] Detected device we're looking for "1532:005c"
21:36:40 [INFO] Display '0' set to 0xf
21:36:40 [ERROR] Failed to set display '1' to 0xf

davertron on Sep 10, 2020