Public bug reported:

I installed ddcutil and I was successfully able to detect my HDMI
monitor and change its brightness. It also detects my laptops builtin
display but does not detect my secondary dell monitor.

The dev of ddcutil said
> ...the problem is either in the docking station hardware, or the i915 driver.

see ddcutil-interrogate(1).log for the verbose ddcutil information

This is the ddcutil github issue
https://github.com/rockowitz/ddcutil/issues/491

Here is some context of my setup. Both my primary and secondary monitors
are connected directly to my dell WD22TB4 dock and the dock is connected
directly to my dell xps 13.

os: Ubuntu 24.04.1 LTS (Noble Numbat)
kernel: 6.8.0-52-generic

dock: Dell Thunderbolt Dock - WD22TB4 (connected to thunderbolt port on laptop)
laptop: Dell XPS 13 9310

monitor primary:   cord_type=HDMI con=DP-7 model=DELL S2725DS
monitor secondary: cord_type=DP   con=DP-5 model=DELL S2725DS (not detected by 
ddcutil)

ddcutil version: 2.1.4 (installed using apt)

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: i2c-tools 4.3-4build2
ProcVersionSignature: Ubuntu 6.8.0-52.53-generic 6.8.12
Uname: Linux 6.8.0-52-generic x86_64
ApportVersion: 2.28.1-0ubuntu3.3
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Tue Feb 11 14:21:42 2025
DistributionChannelDescriptor:
 # This is the distribution channel descriptor for the OEM CDs
 # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
 canonical-oem-somerville-focal-amd64-20200502-85
InstallationDate: Installed on 2021-06-11 (1342 days ago)
InstallationMedia: Ubuntu 20.04 "Focal" - Build amd64 LIVE Binary 20200502-05:58
ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=xterm-ghostty
 XDG_RUNTIME_DIR=<set>
SourcePackage: i2c-tools
UpgradeStatus: Upgraded to noble on 2024-12-17 (56 days ago)

** Affects: i2c-tools (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug noble wayland-session

** Attachment added: "ddcutil-interrogate(1).log"
   
https://bugs.launchpad.net/bugs/2098032/+attachment/5856599/+files/ddcutil-interrogate%281%29.log

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https://bugs.launchpad.net/bugs/2098032

Title:
   i2cdetect has trouble communicating with external monitor plugged
  into dell dock

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