Consider Replacement for core_freq=250 Setting on Raspberry Pi 4

[EricHigdon]

On the pi4, a core_freq value of 250 is ignored, because the only accepted options are 500 (default) or 600. The enable_uart=1 setting is a workaround, but I'm not sure I want to build that into the setup wizard since it is a bit hacky.

[dexer12]

I already found some information, where it seems that the Pi4 is underclocking the core_freq to 200mhz when in idle mode. I could not test it yet, but i would give this a try:

core_freq=250 core_freq_min=250

As far as i understood what i've found. the core_freq=250 sets the core freq correctly but regarding the other behaviour of the Pi4 it will use a core_freq of down to 200 while being idle. So maybe this could be fixed with setting the core_freq_min.

[EricHigdon]

@dexer12, can you share links to the docs where you found this info?

[dexer12]

I first found it here: https://github.com/raspberrypi/linux/issues/3381#issuecomment-568546439

And in the documentation from raspberry here: https://www.raspberrypi.org/documentation/configuration/config-txt/overclocking.md

where you could see that the core_freq changes for example when enableing 4k 60 FPS Hdmi Mode.

[EricHigdon]

https://github.com/jgarff/rpi_ws281x/issues/381 Indicates that this issue can be resolved by setting

core_freq=500 core_freq_min=500

I’ll give this a shot soon and implement it into the wizard if it works.

Note to self: I need a way to show the wizard again to someone who has already seen it if they are on an rpi4.

[cp2004]

Can confirm that this works on all my Rpi4s, you need both as it clocks down when not at high demand (Like higher end CPUs) and screws up the timing.

[unexist]

I cannot confirm, that this solution works for my Ender 3 Pro/Rasp 4B and according to the docs this combination isn't supported at all:

https://www.raspberrypi.org/documentation/configuration/config-txt/overclocking.md

core_freq is ignored as stated in the docs:

Changing core_freq in config.txt is not supported on the Pi 4, any change from the default will almost certainly cause a failure to boot.

And the allowed values for core_freq_min are 250 and 275, according to the table in the docs.

Additionally, when I use the suggested combination, I cannot establish any connection between my Ender and my 4B.

So what works for me so far is to just use core_freq=250 and core_freq_min=250, although I cannot say if the progress bar works at all, my current print job is at 0%.

(Will update later, if I can see any progress tho.)

Update: My progress bar is working again. Update2: Looks like I forgot the initial suggestions, which works perfectly for me. :o