Changing resolution and refresh rate on the fly on the Pi 4 - any news?

Amplifuzz

I'm porting a script I made for the older Pis to the 4, to dynamically change the monitor refresh rate depending on a specific game or system in Retropie.

The main part goes like this:

vcgencmd hdmi_cvt $x_res $y_res $refresh 0 0 0 1
tvservice -e "DMT 87"
fbset -depth 8
fbset -depth 16

It's always worked flawlessly on the 3b+, but results in a black screen on the Pi 4. Apparently it can't work anymore due the switch to FKMS. Is there a way to do it on the Pi 4 yet? Or a way to disable FKMS? Emulationstation refuses to launch if I do that in config.txt

Amplifuzz

I'm porting a script I made for the older Pis to the 4, to dynamically change the monitor refresh rate depending on a specific game or system in Retropie.

The main part goes like this:

vcgencmd hdmi_cvt $x_res $y_res $refresh 0 0 0 1
tvservice -e "DMT 87"
fbset -depth 8
fbset -depth 16

It's always worked flawlessly on the 3b+, but results in a black screen on the Pi 4. Apparently it can't work anymore due the switch to FKMS. Is there a way to do it on the Pi 4 yet? Or a way to disable FKMS? Emulationstation refuses to launch if I do that in config.txt

mitu

Please don't double post, it's enough to post your topic in a single category.

mitu

RetroArch recently merged a change to allow the resolution switching based on custom resolutions ( based on a hdmi_timings config ) - 11590.
RetroArch also has an CRT Switch Resolution feature, supporting the KMS/DRM video drivers for the Pi4 is not yet part of it, but it's planned/worked on.

myzar

@mitu I'm very interested to this, i use a crt cab and we miss resolution switching badly , so i've tried adding

crt_switch_timings = "1920 1 152 247 280 240 1 3 7 12 0 0 0 60 0 40860000 1"

in retroarch.cfg , but doesn't seem to do anything useful

https://pastebin.com/W9i88zUW

Is this supposed to work with vc4-fkms-v3d ?

mitu

@myzar said in Changing resolution and refresh rate on the fly on the Pi 4 - any news?:

Is this supposed to work with vc4-fkms-v3d ?

I think so, but the change is in RetroArch's master branch and it will be available in version 1.9.1, while RetroPie has 1.8.8.

myzar

@mitu yeah i know but i've compiled master Built: Dec 3 2020 Version: 1.9.0 Git: db2cd8f , this is newer than the merged commit referred here , should i ask in the pull https://github.com/libretro/RetroArch/pull/11590 if it is going to do anything ?

mitu

@myzar Make sure you have video_fullscreen = yes set also, if that still doesn't work, you can add your log to the PR and ask the author - maybe further configuration is needed.

EDIT: you should also make sure you're editing the correct retroarch.cfg, the log file doesn't show which one is used.

myzar

@mitu my bad i was using the vulkan driver it doesn't do anything with that, i have switched back to gl and now it does something

[INFO] [DRM]: Connector 0 assigned to monitor index: #1.
[INFO] [DRM]: Mode 0: (FIXED_MODE) 320 x 240, 60 Hz
[INFO] [GL]: Found GL context: kms
[INFO] [GL]: Detecting screen resolution 1920x240.
[INFO] [DRM]: custom mode requested: CRT_1920x240_60
[INFO] [EGL] Falling back to eglGetDisplay
[INFO] [EGL]: EGL version: 1.4
[INFO] [EGL]: Current context: 0xaa81ffa8.
[INFO] [KMS]: New FB: 1920x240 (stride: 7680).
[INFO] [GL]: Vendor: Broadcom, Renderer: V3D 4.2.
[INFO] [GL]: Version: OpenGL ES 3.1 Mesa 21.0.0-devel (git-872c4bcd27).
[INFO] [GL]: Using resolution 1920x240
[INFO] [GL]: Default shader backend found: glsl.

But it's pretending that it switched res it's delusional like fbset , let me try to explain even tho english isn't my native language , it thinks to be @ 1920x240 but it's still drawing @ 320x240 , the result is that everything is super mega giant like you zoomed with a 4x multiplier.
The point is that isn't really switching res , i'm sure because i can put bogus values which my monitor wouldn't be able to sync. Such a shame i was so excited we miss pixel perfects res badly on the rpi4

myzar

it was too good to be true :( i was right it doesn't work https://github.com/libretro/RetroArch/pull/11590#issuecomment-743402918