Pi4 Bug: can't change resolution on the 2nd HDMI port

Pxtl

Hey,

Coming back to Pie after suffering for months with Lakka (libreelec is traaaaash). Quickly ran into a bug:

As you know, pi4 emulation is unusably slow on 4k TV. However, if I changed the resolution config in raspi-config I just got a black screen of death after rebooting. I was able to recover by using ssh to edit config.TXT but every setting I tried either failed to change resolution and left me stuck at 4K or gave me the black screen of failure.

Eventually I tried switching HDMI ports. That worked on Lakka too, but Lakka made it more obvious by giving me complete 100% failure if I used the wrong port, instead of "sort of works until you want to change resolution" which is more subtle and difficult to debug than "just plain broken".

Fail faster and harder is probably a good idea here, since "almost kinda works" is more frustrating than "just broken"

Anyhow, should I log a bug in the GitHub? It says to post here first.

mitu

I don't see how that's a RetroPie issue - the 2nd port should work fine, even audio. Post your config.txt.

Pxtl

Just confirmed it again. 2nd port is stuck at 4K, first port works fine at going to lower res.

Config.txt in paste: https://pastebin.com/KfBBTZuK

mitu

Since the Pi4 has 2 (micro) HDMI ports, the options for the 2nd port should be suffixed with :1 (see https://www.raspberrypi.org/documentation/configuration/config-txt/video.md). Try adding this to your config.txt

hdmi_group:1=2
hdmi_mode:1=85

EDIT: You can also use a conditional section (should be added last).

[HDMI:1]
hdmi_group=2
hdmi_mode=85

Pxtl

@mitu Neat! But the raspi-config tool didn't seem to know that. This is the first I've seen of :1

SRossi

just wanted to say I had the same problem. maybe the raspi config tool can be fixed so it can handle this situation?

mitu

@SRossi Maybe, but raspi-config is not a RetroPie project, it's maintained by Raspbian (Raspberry OS).

SRossi

sure! didn't want to imply that, it just was a major roadblock for me yesterday and today and a lot of searching around just showed that a bunch of people had the same problem. the solutions with manually editing the config file sure help but it would have been just so much easier if I could have set it in the menue. not because editing the file is difficult, more like you don't think of it because everything else just works like it should (well, beside the playstation classic controller not working despite being a simple USB device) and the config tool just blanking out is confusing. honestly if the whole system wouldn't crawl around at around 10 - 15fps at 4k you wouldn't even notice the problem is there to begin with. I'll search if the problem is known at Raspbian.