Monitors say 1920x1080@60 is out of range

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Don't Panic. Please wash hands.
  • I'm having an issue with the Indivision AGA MK3 where two of my monitors say the timing for the 1920x1080@60 resolution is out of range. One is a Dell U2312HM (1920x1080 native resolution) from 2011 and the other an HP Z27 (3840x2160 native resolution) that I got new this year. A Dell P2415Q from 2015 doesn't have the issue.

    The super weird thing is that these are actually one of the monitors' EDID resolutions. They all report this in EDID, which also matches the 1920x1080@60 preset:

    I checked the Z27's manual, and it says 1920x1080@60 should have a horizontal frequency of 67.5 kHz, so that's slightly different than these timings.

    Could it be that the EDID data is changed from what the monitor reported at some point?

    Also note that the above doesn't match any of the 1920x1080@60 timings from the Video Timings Calculator. I couldn't try the CVT timings because those require a pixel clock of 173 MHz, but I did try the CVT-RB timings and those also didn't work.

    Strangely, both do monitors work with the exact same settings except a 125 MHz pixel clock so the vertical refresh rate becomes 50 Hz (to be more compatible with Amiga PAL modes).

    I tried some stuff some weeks ago when I got the MK3 and don't remember seeing this issue on these monitors or my 4K TV. I think I tried 1920x1080@60 then but I can't be sure. Since then I've only been using the P2415Q monitor which doesn't have the issue, until today.

    I tried restoring the August 24 firmware but that didn't change anything.

  • It's not impossible for EDID data to be plain wrong. Did you try the PRE-mode for 1920x1080@60Hz? That's known-good with cheap TVs and might have a timing that your Dell monitor likes.

  • Yes, I tried that, and I also confirmed the PRE mode is the same as the EDID mode for all monitors.

    I do find it curious that those EDID and PRE modes are all the same for monitors from 2011, 2015 and 2018. At the same time, the 2011 monitor (which doesn't work) and the 2015 one (which does work) say horizontal 67.5 kHz and pixel clock 148.5 MHz. The 2018 one (which doesn't work) also says 67.5 kHz but doesn't mention the pixel clock in the manual.

    The 67.5 kHz doesn't match the EDID info, which makes me suspect that the EDID info the setup tool shows is somehow different from the info the monitors send. It would be very strange that three monitors from two different makers send the same wrong info, especially if using that info doesn't work for two of the three. (Not impossible of course, but certainly not the obvious explanation.)

  • After the 1.6 update it looks like the EDID readings are different. I retried with one monitor, but still the same result. However, that's a DVI monitor and although I selected no audio output, I want to make sure that that's actually what's being used so I want to do some more checking, and also with the other monitor. However, as I'm currently doing surgery on my A3000, this will have to wait a bit.

    (It would of course be ideal if the audio can be disabled automatically for DVI monitors.)

  • (It would of course be ideal if the audio can be disabled automatically for DVI monitors.)

    This would have to happen in a software that runs on the Amiga, as the space in the FPGA is too small. However, there#s no clear indication where this information can be found in the EDID data. If you have a good source of information, please share it! I currently have an industrial project where an RPi is used without a monitor, and whenever I connect a DVI screen, I need to reboot that RPi in order to get a proper picture. I'm assuming that it detects the monitor's (in)capability to accept audio, so it's possible. However, it may be some heuristic or even a database-approach.

    Again, if you happen to know more, you'd help us by sharing that documentation.

  • I tested with all my displays. The Dell P2415Q (my normal display) doesn't have any problems, unless I'm mistaken the LG OLED TV is also fine as well as the old Philips 1280x1024 DVI monitor, which actually handles 1920x1080, which is way higher than its native resolution.

    The problems are with the DVI Dell H2312UM and HDMI HP Z27. Especially the latter is extremely picky. These two don't accept their own EDID 1920x1080@60 resolution, not under 1.5 nor 1.6, even though the timings are slightly different between the EDID data as read by thesetwo versions.

    As for detecting audio capability: over here it says that bit 6 at position $83 indicates "basic audio" support.

    I checked the EDID data from my five displays, and it turned out that the two DVI ones have all $FF bytes above $80:

    The HDMI ones (supporting audio) all have real looking data here and bit 6 at $83 is indeed set.

    (Yes, this hex editor was the best one I tried off of Aminet. :))

    I'd say a good approach for safety would be to have something you could run in your user-startup that checks the monitor's EDID info and disables audio if the bit is unset or the EDID info doesn't include this bit.

    Another option would be to have separate settings for each monitor, so different settings are loaded when a different monitor is detected, with safe defaults for unknown monitors.

    I have included a zip file with all the EDIDs.

  • Another option would be to have separate settings for each monitor, so different settings are loaded when a different monitor is detected, with safe defaults for unknown monitors.

    Actually that shouldn't be too hard to script. The IndivisionAGAmk3 tool can already read the EDID and then it's just a matter of checking for one or more known monitor names and copying over a different settings file.

    However, what would be helpful here is if the tool could output the name of the monitor, that saves having a separate utility that parses the saved EDID file to find the monitor name.