monitor loses DVI after KMS / EDID issue?

[Benjamin Slade]

I've acquired a couple of HP L1750 monitors, which have VGA & DVI inputs. The VGA inputs work without issue. However, the DVI input only works until Kernel Mode Setting (KMS) occurs, after which it declares it isn't receiving a signal and enters sleep mode. I've tested two different HP L1750 monitors, with different DVI cables and different DVI source providers (i.e. different video cards) and the same behaviour obtains.

I've also tried manually specifying the appropriate resolution via a kernel boot option, e.g.:

video=DVI-D-0:1280x1024 at 60e

As well as manually configuring xorg.conf (relying on the the output of `hwinfo --monitor`) to:

--8<---------------cut here---------------start------------->8---
Section "Device"
    Identifier  "DefaultDevice"
EndSection

Section "Monitor"
    Identifier  "DefaultMonitor"
    HorizSync   24-83
    VertRefresh 50-77
    Option      "TargetRefreshRate" "60"
    Option      "DDC"   "off"
    Option      "DPMS"  "off"
    Option      "DefaultModes"  "on"
    Option      "PreferredMode" "1280x1024"
EndSection

Section "Screen"
    Identifier  "DefaultScreen"
    Device      "DefaultDevice"
    Monitor     "DefaultMonitor"
EndSection
--8<---------------cut here---------------end--------------->8---

The issue seems to be[1] that the DVI of this monitor is defective without a special Windows driver[2] to fix it.

How do I determine what the appropriate EDID should be? And how do I go about loading it into RAM after boot?

[1] https://www.linuxquestions.org/questions/linux-hardware-18/second-monitor-connected-as-dvi-enters-sleep-mode-during-boot-and-never-comes-out-of-sleep-%3B-but-works-with-vga-connection-4175654157
[2] https://answers.microsoft.com/en-us/windows/forum/windows_7-performance/display-problem-with-external-monitor-hp-l1750/7df57883-4777-49a3-a356-72aa4efa79e2

-- 
Benjamin Slade - https://babbagefiles.xyz
  `(pgp_fp: ,(21BA 2AE1 28F6 DF36 110A 0E9C A320 BBE8 2B52 EE19))
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