RPi4B u-boot based booting and hw.cpufreq.voltage_core and dev.cpu.0.freq use: able to use 2000 MHz

[tech-lists]

On Sat, Sep 26, 2020 at 12:37:45AM -0700, Mark Millard via freebsd-arm wrote:
>I got access to a 4 GiByte RPi4B that does not have modernized
>eeprom contents. With it I was able to do a u-boot based boot
>of head -r365932 based on the msdosfs on a older microsd card
>that had materials from 2020-Jul-13 (u-boot.bin) and 14 (RPi4B
>materials). I updated EFI/BOOT/bootaa64.efi . The u-boot.bin
>is from my build of sysutils/u-boot-rpi4/ (no local changes).
>
>In this context . . .
>
>I added over_voltage=6 and arm_freq=2000 to config.txt and it
>ends up looking like:
>
>arm_control=0x200
>arm_64bit=1
>dtoverlay=disable-bt
>dtoverlay=mmc
>device_tree_address=0x4000
>kernel=u-boot.bin
>armstub=armstub8-gic.bin
>over_voltage=6
>arm_freq=2000
>
>
>Booting based on that resulted in:
>
>dev.bcm2835_cpufreq.0.freq_settings: 2000/-1 600/-1
>dev.cpu.0.freq_levels: 2000/-1 600/-1
>dev.cpu.0.freq: 600
>
>And:
>
># sysctl dev.cpu.0.freq=2000
>dev.cpu.0.freq: 600 -> 2000
>
>worked. (Without the over_voltage it reports 600 and then
>hangs.) Having /etc/sysctl.conf list dev.cpu.0.freq=2000
>works.

Exellent! On the basis of your post I went ahead and removed from config.txt
three lines, then added two and rebooted.

It's now this:

arm_control=0x200
arm_64bit=1
dtoverlay=disable-bt
dtoverlay=mmc
device_tree_address=0x4000
kernel=u-boot.bin
armstub=armstub8-gic.bin
over_voltage=6
arm_freq=2000

before, when it didn't work, it had this:
[same as above], apart from
gpu_mem=16
over_voltage=6
arm_freq=2100

In creating the freebsd instance I followed these instructions for 8GB
https://lists.freebsd.org/pipermail/freebsd-arm/2020-August/022162.html
and applied D26344. /etc/rc.conf has powerd loaded

I was particularly interested in getting this clocked to a reasonable speed as
it's used to build packages with poudriere based on arm7 and aarch64 for
-current.

seems very stable so far:

  2:36p.m.  up 45 mins, 1 user, load averages: 6.51, 3.57, 2.92
Sat 26 Sep 2020 14:36:14 BST
dev.cpu.0.temperature: 65.0C
dev.cpu.0.freq_levels: 2000/-1 600/-1
dev.cpu.0.freq: 2000

rpi4 is in a FLIRC case for cooling, no fan. 24 degC/44%rh ambient.

best, 
-- 
J.
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