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Date: Sun, 29 May 2022 04:14:37 +0200
Message-Id: <CKBVSP4T1JAQ.3FFPUBSYCCXS8@sumire>
Cc: 
Subject: Re: Raspberry PI cpufreq
From: "alice" <alice@ayaya.dev>
To: "Jerome Marc" <marcjero@yahoo.com>,
 <~alpine/users@lists.alpinelinux.org>
References: <CAD1Ag0ytC8yoOpadYtxwaMCG18u168x1fc_chrqW3wqrO4rayw.ref@mail.gmail.com> <CAD1Ag0ytC8yoOpadYtxwaMCG18u168x1fc_chrqW3wqrO4rayw@mail.gmail.com>
In-Reply-To: <CAD1Ag0ytC8yoOpadYtxwaMCG18u168x1fc_chrqW3wqrO4rayw@mail.gmail.com>

On Sun May 29, 2022 at 1:16 AM CEST, Jerome Marc wrote:
> Hi,
>
> I just installed Alpine 16 on an old Raspberry PI B.
> I want to use the ondemand governor and set the freq between 100 and 700.
> Unfortunately it looks like the arm_freq_min is ignored.
> if I set :
> arm_freq=3D700
> arm_freq_min=3D500
>
> cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
> returns 700000 only
>
> But if I set
> arm_freq=3D500
>
> cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
> returns 700000 500000
>
> Strange isn't it ? Did I misunderstand something? Or is there a bug in th=
e
> fernel/firmware ?

https://www.raspberrypi.com/documentation/computers/config_txt.html is
your friend :)

i don't remember which gen the Pi B is from (i assume 1?), but it is not
recommended to ever set the minimum below the default, nor are there any
real power savings from it (and it's not supported). so, just keep it at
the default of 700.

as for where the issue lies, it's in the rpi firmware that reads the
values and applies things- if it ignores it, then it's just ignored,
unrelated to the kernel.