Date: Fri, 19 Mar 2021 11:29:51 -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: <AD2BCC4D-F0A2-40F6-ABB8-2F5B08ED47D4@yahoo.com> In-Reply-To: <9DB699E3-5977-4651-B3D2-26343F202F2D@yahoo.com> 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> <9DB699E3-5977-4651-B3D2-26343F202F2D@yahoo.com>
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On 2021-Mar-19, at 11:13, Mark Millard <marklmi at yahoo.com> wrote: > > 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: >>> >>> 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 >>> >>> So somewhat under 9 hours. >>> >> >> So my figures (~17 hours) seem reasonable for a default clocking. >> I thought maybe I'd done something wrong. >> >> 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? > > See: > > https://www.raspberrypi.org/documentation/configuration/config-txt/overclocking.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. Back to temperature. See: https://www.raspberrypi.org/documentation/hardware/raspberrypi/frequency-management.md It indicates that 85C is the maximum temperature, though lower figures can be set. It also reports that a form of throttling starts at 80C by default. The RPi3B+ also has a soft limit that changes the 1.4GHz to 1.2 Ghz and the operating voltage is slightly reduced: configurable temp_soft_limit but by default 60C. For the RPi4B, "there is currently no soft limit defined". === Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar)home | help
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