Date: Thu, 18 Mar 2021 17:28:27 +0000 From: tech-lists <tech-lists@zyxst.net> To: freebsd-arm@freebsd.org Subject: Re: RPI4 clock speeds and serial port Message-ID: <YFONu3Ry0o6VlV92@ceres.zyxst.net> In-Reply-To: <20210318170053.GA26688@www.zefox.net> References: <20210318170053.GA26688@www.zefox.net>
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--bnhWvNSqWpsW7SJ5 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline Content-Transfer-Encoding: quoted-printable hi, On Thu, Mar 18, 2021 at 10:00:53AM -0700, bob prohaska wrote: >/boot/msdos/config.txt contains > >root@nemesis:~ # more /boot/msdos/config.txt >[all] >arm_64bit=3D1 >dtparam=3Daudio=3Don,i2c_arm=3Don,spi=3Don >dtoverlay=3Dmmc >dtoverlay=3Ddisable-bt >device_tree_address=3D0x4000 >kernel=3Du-boot.bin > >[pi4] >#hdmi_safe=3D1 >armstub=3Darmstub8-gic.bin > >Can one change the cpu speed without disturbing the serial console >by using something like > >arm_freq=3D1750 > >in config.txt, provided adequate cooling provisions are made? I have this config.txt on both a rpi4 stable/13 and main/14. I have a flirc case on stable/13 and one of those cases that looks like armour made from solid metal on main/rpi4. In both cases, the approved 5.1V @3.1W power supply is used. The highest temp I've seen under load is 72 degC and that's at 25 degC=20 ambient. On both machines my config.txt looks like this: arm_control=3D0x200 dtparam=3Daudio=3Don,i2c_arm=3Don,spi=3Don dtoverlay=3Dmmc dtoverlay=3Dpwm dtoverlay=3Ddisable-bt device_tree_address=3D0x4000 kernel=3Du-boot.bin over_voltage=3D6 arm_freq=3D2000 sdram_freq_min=3D3200 In order to clock it, I need to enable powerd on startup in /etc/rc.conf: powerd_enable=3D"YES" Because I also want that higher clock to run as much as possible, I tell powerd to have an absurdly low trigger to get the clocked speed: powerd_flags=3D"-r 1" and here's the clocked speed: % sysctl -a | fgrep cpu.0 dev.cpu.0.temperature: 49.6C dev.cpu.0.freq_levels: 2000/-1 600/-1 dev.cpu.0.freq: 2000 dev.cpu.0.%parent: cpulist0 dev.cpu.0.%pnpinfo: name=3Dcpu@0 compat=3Darm,cortex-a72 dev.cpu.0.%location:=20 dev.cpu.0.%driver: cpu dev.cpu.0.%desc: Open Firmware CPU > I'd rather not complicate use of the serial console at this point not sure why the serial console would be a factor. I have a console-wired rpi4 running main/14 and I never considered it. I console into this machine like this: cu -l /dev/cuaU0 -s 115200 --=20 J. --bnhWvNSqWpsW7SJ5 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEE8n3tWhxW11Ccvv9/s8o7QhFzNAUFAmBTjbIACgkQs8o7QhFz NAXajQ//ZnvsuasHLoBYoz9npTqsw6D6HbMrBJkgDjEnGvVAYI4+PuZ4wEk/MRoC TxN9P7mkr0vWw3bfQcb82HOSj6PdSmRSHTyfUKUI1tArgdR23t0u1cTH8dYmZZ4h chWfDqbqGdMBmzqwMzdzGT9W6hzrtwU1XnMVLTOWtq125BgjKmk93+KUGIpjsYCc WY1nshprphxo2dgH+MvP/SWw1i9fHJEZjLchKzUClHY0v1K7V5PJckYiUYzYNIFj rErsHhQVE6F3nhFT+wHhan0lu5pTG14mGB65gV1m95V7XfGPsgmyD5bWbnt/RUWM uf4HMqyQfTppC9nQfmV7j8FYNLg+Gtx5YXta9Wd3ftYZ1K3tqA29pEYwLAQ6c0NC 8aWm5yQoFLzSOodMoDcXLy6IFHyeR6lH3fuB6tlHlKaN7VCOClVFVJJvvL0Hnj/V Bw1qcPxifB9gbObaoHq1JpEB9kc1kaLScTD0NXG2brNaNXGbICpiiK2tJ7Zctjht Rsl/XdHDuNjULFYA2GMpVTY0n9lLUzwoTCijgmJuSr/5mb3XaJj+70qz8P4uSOM3 m09Rf4wxDMZgxpDR7FbgGGFLFcejiKKBM5X2pu+CgdkGP2vh7OtWmU0R4uDVyNwG kDX7CQD786VR8HXsljQg+eKDw32NZEbCykUhgTELGZkB/p1GWnc= =2fbt -----END PGP SIGNATURE----- --bnhWvNSqWpsW7SJ5--
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