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Date:      Fri, 19 Mar 2021 11:13:49 -0700
From:      Mark Millard <marklmi@yahoo.com>
To:        bob prohaska <fbsd@www.zefox.net>
Cc:        freebsd-arm <freebsd-arm@freebsd.org>
Subject:   Re: RPI4 clock speeds and serial port ( temperatures idle and -j4 buildworld buildkernel )
Message-ID:  <9DB699E3-5977-4651-B3D2-26343F202F2D@yahoo.com>
In-Reply-To: <20210319174359.GA38899@www.zefox.net>
References:  <20210318170053.GA26688@www.zefox.net> <9FFA0A51-C0B7-4121-95CA-B98669809007@yahoo.com> <E4CF6642-CB70-4495-A865-05469953561C@yahoo.com> <EA6BE351-98F5-4446-BA4D-948F04EDFD3B@yahoo.com> <81AC0353-258C-41C3-86B1-C133E33D97E3@yahoo.com> <20210319174359.GA38899@www.zefox.net>

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On 2021-Mar-19, at 10:43, bob prohaska <fbsd at www.zefox.net> wrote:

> On Thu, Mar 18, 2021 at 10:14:26PM -0700, Mark Millard wrote:
>>=20
>> World build completed on Thu Mar 18 21:31:44 PDT 2021
>> World built in 29705 seconds, ncpu: 4, make -j4
>> . . .
>> Kernel build for GENERIC-NODBG completed on Thu Mar 18 22:10:02 PDT =
2021
>> Kernel(s)  GENERIC-NODBG built in 2298 seconds, ncpu: 4, make -j4
>>=20
>> So somewhat under 9 hours.
>>=20
>=20
> So my figures (~17 hours) seem reasonable for a default clocking.
> I thought maybe I'd done something wrong.
>=20
> For now I'll leave the clocking alone. But some puzzles remain:
> It appears that the CPU and the GPU have separate clocks. Can they
> be set separately, and does the GPU have any practical effect on
> FreeBSD's behavior once boot is complete?=20

See:

=
https://www.raspberrypi.org/documentation/configuration/config-txt/overclo=
cking.md

It says that setting gpu_freq sets core_freq and also says:

QUOTE
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.
END QUOTE

and:

QUOTE
It is recommended when overclocking to use the individual
frequency settings (isp_freq, v3d_freq etc) rather than gpu_freq,
as since it attempts to set core_freq (which cannot be changed on]
the Pi 4), it is not likely to have the desired effect.
END QUOTE

There is more about the relationships to hdmi_enable_4kp60 and
enable_tvout.

=3D=3D=3D
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)




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