Still having difficulties with HDMI output on some displays using the Pi 400

[markiemarcus]

#326

A continuation of this, for what it's worth. 1.7.0 does not resolve the issue. Perhaps it can't be fixed and given how rare an issue it seems to be, I completely understand just moving on haha. But I do have some further diagnostic info if it's of any use:

I can get an image on the monitor if I boot the Pi 400 on a working display, then keep it powered on and hotplug the HDMI cable into the monitor. Zero issues, all resolutions seem to work. But of course, the moment you power cycle the Pi 400, there's no signal on the monitor again.

Appreciate your help so far in any case. It is a mystery to me! I have never encountered this before.

Edit: Some more strangeness. If I switch the display mode to dual screen clone at 1080p60 and connect only the working display to the HDMI port closest to the SD card, the boot progresses as normal (under 30 seconds) and works as expected. But when I connect the second, non-working monitor at the same time, the boot takes several minutes before eventually showing on the TV, but not on the monitor. If I switch the HDMI connections and make the non-working monitor the port closest to the SD card, it doesn't appear to boot at all and no image is displayed on either screen. It appears to be stopping the boot entirely.

Edit 2: There's more haha. As of 1.7, If I leave the boot on the monitor for 3-4 minutes now, it does eventually display. It's just several minutes slower to do so than every other display. I can live with that. How odd though!

[rhester72]

This may be a bad interaction between the Pi firmware and your display.

Try booting your 400 with a fresh-and-updated Raspberry Pi OS distribution and manually updating the firmware.

[markiemarcus]

Thanks for the suggestion. I did a full update of Trixie as a sanity check a few weeks back (which boots and posts a signal immediately), but I've just checked it again. Both the bootloader and the firmware are the latest releases.

[thatguywiththekids]

1080p60 is not an exact description of one signal format, it matches more than one. Do you have an older TV, like a Sony from the early 2000s? Never mind, I see you named your monitor in the other issue.

[markiemarcus]

Monitor (the one with the issue): MSI MP341CQ. 1440p100
4K TV (no issues): Hisense 65A85HTUK. 4K120
1080p small TV (no issues): Some no-brand nonsense. 1080p60

They're all fairly new. I should add that even the NRR functionality works. Yes, even on the monitor. I just have to wait 3-4 minutes for it to display a signal on boot. It always 3-4 minutes as well; I have timed it. It's never faster than that and never slower.

[thatguywiththekids]

I am going to guess that your monitor EDID (basically the info about what the monitor can do) is incomprehensible to RePlayOS for some reason and then after some time it falls back to something safe that works.

[rtomasa]

It sounds like a monitor firmware/edid issue to me, but I'm curious to see what information is reporting it to the Raspberry. Could yopu please follow these instructions and provide the log info? https://www.replayos.com/loginfo/

[markiemarcus]

I will do this week, thanks. After setting that up, presumably you need a log from a cold boot where there display takes 3-4 minutes to show?

[rtomasa]

Same results should be achieved by following the instructions provided in the above link. No need for real coold boot.