Troubleshooting • Pi 500 HDMI works in firmware, but not in Linux

I've been unable to get my Pi 500 working with any of my HDMI displays.

The displays I've tried are:
- LG 27UP600-W (2160p monitor)
- LG OLED48B4 (2160p TV)
- Dell P2416Db (1440p monitor)

For all of these displays, the firmware diagnostic screen appears fine. But when the OS boots, HDMI stops working. The only thing I see is on the Dell monitor, there is an empty text screen with a cursor that disappears after a brief moment. The monitors then both report no signal on the HDMI. The TV shows an "invalid format" error.

I've attempted:
- Using one or the other HDMI port
- Leaving the HDMI unplugged for a minute to wait for the system to fully boot
- Disabling plymouth and removing "quiet" from the kernel command line
- Forcing a video mode with `video=HDMI-A-1:1280x720M@60`
- Using the `vc4-fkms-v3d` overlay (removing the `video=` line)
- Specifying an HDMI mode with `hdmi_group=2` and `hdmi_mode=85` (720p)
- Flashing another SD card with Ubuntu 24.04 desktop and trying to boot that as-is

Nothing has worked so far. As stated, it works in the firmware. The firmware has no issues displaying on any of the three displays. I've spent the better part of a day fighting this, to no avail.

Statistics: Posted by illucid-matthew — Sun Dec 15, 2024 7:46 pm

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