Notes on Specific Monitors
This page a location where ddcutil community members can consolidate what has been learned about specific monitors. It is intended to replace website page Notes on Specific Monitors.
As reported by user @rnwst:
ddcutil didn't recognize my second display, which was the second/last display in a USB-C MST setup. The first display is a Dell U2723QE. This was despite my user having read-write permissions for all i2c devices, and the i2c-dev kernel module being loaded.
The solution turned out to be a setting in the OSD menu of the Dell U2723QE. 'Display' -> 'Multi-Monitor Sync' was turned on. Once it was turned off, everything worked correctly.
Monitor supports DDC via HDMI and both DisplayPorts. Unfortunately, the protocol doesn't allow you to properly switch between DP1 and DP2 - probably due to custom PIP mechanisms.
Do not implement DDC/CI on DisplayPort inputs, only on HDMI. See webpage Notes on Specific Monitors and this reddit post.
Feature x60 (Input Source) actual values:
| Port | Feature value |
|---|---|
| HDMI | x05 |
| DisplayPort | setvcp requires x06, but getvcp reports x0f |
MCCS (VCP) version reported:
| Source | Version |
|---|---|
| capabilities string | 2.2 |
| feature xdf | 2.2 |
Reported by user @ehdoyle