That’s unfortunate. I looked it up a little bit more and it seems that it’s not just a matter of binary editing the EDID file and removing entries. EDID files contain at least a CRC, which would need to be recalculated correctly for it to work.
If you look inside the kernel sources, you’ll find this directory:
Documentation/EDID/
Inside it you will find several files that generate some monitor modes, together with a makefile to create the binaries. With that, I think you would need to have the proper data of your monitor for the correct mode you need and input it in a new file, and then generate a new EDID file.
Please see this answer for more info:
To check if the EDID you generated is indeed broken, I would suggest you to install the read-edid package on your linux distribution and then use something like:
cat edid.bin|parse-edid
You can also compile read-edid for the target and use it to parse the edid directly from the sysfs:
$ cat /sys/class/drm/card1-HDMI-A-1/edid|parse-edid
Checksum Correct
00000000 00 ff ff ff ff ff ff 00 41 0c cd c0 8a d5
Section "Monitor"
Identifier "PHL 193V5"
ModelName "PHL 193V5"
VendorName "PHL"
# Monitor Manufactured week 24 of 2021
# EDID version 1.3
# Digital Display
DisplaySize 410 230
Gamma 2.20
Option "DPMS" "true"
Horizsync 30-83
VertRefresh 56-76
# Maximum pixel clock is 170MHz
#Not giving standard mode: 1280x1024, 60Hz
#Not giving standard mode: 1280x720, 60Hz
#Not giving standard mode: 1280x960, 60Hz
#Extension block found. Parsing...
Modeline "Mode 12" +hsync +vsync
Modeline "Mode 0" +hsync +vsync
Modeline "Mode 1" 25.200 640 656 752 800 480 490 492 525 -hsync -vsync
Modeline "Mode 2" 27.027 720 736 798 858 480 489 495 525 -hsync -vsync
Modeline "Mode 3" 27.027 720 736 798 858 480 489 495 525 -hsync -vsync
Modeline "Mode 4" 27.027 1440 1478 1602 1716 480 484 487 525 -hsync -vsync interlace
Modeline "Mode 5" 27.027 1440 1478 1602 1716 480 484 487 525 -hsync -vsync interlace
Modeline "Mode 6" 27.000 720 732 796 864 576 581 586 625 -hsync -vsync
Modeline "Mode 7" 27.000 720 732 796 864 576 581 586 625 -hsync -vsync
Modeline "Mode 8" 74.250 1280 1720 1760 1980 720 725 730 750 +hsync +vsync
Modeline "Mode 9" 27.000 1440 1464 1590 1728 576 578 581 625 -hsync -vsync interlace
Modeline "Mode 10" 27.000 1440 1464 1590 1728 576 578 581 625 -hsync -vsync interlace
Modeline "Mode 11" 74.250 1280 1390 1420 1650 720 725 730 750 +hsync +vsync
Modeline "Mode 13" -hsync -vsync
Modeline "Mode 14" -hsync -vsync
Option "PreferredMode" "Mode 12"
EndSection
The output above is from my apalis imx8 with a 19" monitor connected to the HDMI port.