1920x1080 display resolution worked and now it doesn't

[scorcoran]

Model: Pi 4 Model B Rev 1.2
OS: Linux raspberrypi 4.19.97

I've had my Pi up and running for a couple weeks (on a monitor, not TV). It started, and has been displaying, in 1920x1080 resolution. I've rebooted several times and it always came up 1920x1080. Today, however, it booted to 1024x768 and I can no longer get it to display in 1920x1080.

Using the Screen Configuration tool it shows 1920x1080 as an option. When I select it my screen blanks, then displays "Input Not Supported" for a few seconds, then reverts to 1024x768.

I also tried setting it with raspi-config from CLI. It had no effect.

I booted in recovery mode and confirmed config.txt has the values
hdmi_group=2
hdmi_mode=82

When exiting recovery mode and continuing to boot I get the same "Input Not Supported" and then the 1024x768 screen.

I've tested the monitor on a different computer and it can display 1920x1080. I tried the Pi on a different monitor and it has the same effect. So I've ruled out a monitor problem.

Any advice is appreciated.
SC

[FTrevorGowen]

Model: Pi 4 Model B Rev 1.2
OS: Linux raspberrypi 4.19.97

I've had my Pi up and running for a couple weeks (on a monitor, not TV). It started, and has been displaying, in 1920x1080 resolution. I've rebooted several times and it always came up 1920x1080. Today, however, it booted to 1024x768 and I can no longer get it to display in 1920x1080.

Using the Screen Configuration tool it shows 1920x1080 as an option. When I select it my screen blanks, then displays "Input Not Supported" for a few seconds, then reverts to 1024x768.

I also tried setting it with raspi-config from CLI. It had no effect.

I booted in recovery mode and confirmed config.txt has the values
hdmi_group=2
hdmi_mode=82

When exiting recovery mode and continuing to boot I get the same "Input Not Supported" and then the 1024x768 screen.

I've tested the monitor on a different computer and it can display 1920x1080. I tried the Pi on a different monitor and it has the same effect. So I've ruled out a monitor problem.

Any advice is appreciated.
SC

Your reference to "recovery mode" suggests that you're using a NOOBS-based install of Raspbian . If that's the case how did you edit/check config.txt? IIRC, there could be more than one such file eg. one for the NOOBS installer itself and one (each) for the O.S.('s) installed.
Trev.

[scorcoran]

Yes, I assume I'm using NOOBs install since I just followed the OOTB instructions and haven't tried installing any other OS. I got the OS from the command
uname -a.

I tried recovery mode after trying everything else. Within recovery mode there is an option to edit config.txt, but I had changed it already using raspbi_config.

I checked the /boot folder. I only see one config.txt, the one that has been modified.

[scorcoran]

Update: I started over. I reinstalled raspbian and went through the setup process again. Unfortunately, no change. Resolution is still 1024x768. However, this time, in the desktop display resolution config screen 1920x1080 isn't even listed as an option. I again went into raspi-config via CLI and set the resolution to 1920x1080. Then upon reboot, I get the same "Input not Supported" message before coming up in 1024x768.

[scorcoran]

One more thought. This could be just coincidence or perhaps somehow the cause. This started when I had to move my monitor and the connecting cables. When reconnecting the monitor to the Pi I decided to plug into the second micro-HDMI port. It would not insert fully, so I just put it back in the first port. Later, upon inspection of the second port I noticed one of the metal prongs inside was bent down preventing the micro-HDMI from inserting. I shut down, disconnected power and carefully tried to bend the prong back into position. That worked, the micro-HDMI would now insert fully into that port, but, if this was the cause, the damage was done. Still no high resolution.

[scorcoran]

Further research here [https://www.raspberrypi.org/documentati ... -config.md] indicates to get 1080p resolution the following must be true:
1. You can only be driving one display. If there are two displays plugged in the rate and resolution drops.
2. That one display must be driven from HDMI0
3. In config.txt you must have this flag, hdmi_enable_4kp60=1

All of those are true for me and I still can't get 1080p, which leads me to this conjecture. The bent lead on HDMI1 is causing the system to sense there are two displays and drop to the lower rate/resolution, even though no cable is actually plugged in. I believe the smoking gun is this 1080p worked perfectly until I tried to connect to HDMI1 with its bent lead, bending it further when trying to insert, and subsequently bending it back.

I've proposed this to the vendor from where I purchased the Pi and asked for an exchange. My confidence is not high. May have to just buy another one.

[scorcoran]

SOLVED:
Turns out this was a HW issue AFAICT. It wasn't the bent lead however. It was that trying to insert the micro-HDMI into the socket with the bent lead apparently damaged the connector. Not bad enough that it wouldn't display, it just wouldn't display at 1080p. After replacing the cable, all was well and displaying at high resolution.

Bonus: despite my interpretation of the documentation, when I tried driving two monitors, they both worked (bending the lead back didn't damage anything) AND the both displayed in 1080p. I was expecting lower resolution, but again, I may be misinterpreting the documentation.

[6by9]

You can drive up to dual 4k30 from the Pi4. If you enable 4k60 then the second screen can only be 1080p.

Getting 1024x768 sounds like the normal behaviour if the Pi can't read the EDID of the monitor so doesn't know what modes it supports. That would be consistent with it being a damaged connection on one or two specific pins of the micro HDMI connector.