Armada 3720 cpufreq bug: request for testing (EspressoBIN, uDPU, ...)

I have a request for testing some patches that fix cpufreq issues on Armada 3720 (EspressoBIN, uDPU, Devel Board, maybe others?).

It concerns top 4 commits of branch a3720-cpufreq-issues of repository
https://git.kernel.org/pub/scm/linux/kernel/git/kabel/linux.git/

(log at https://git.kernel.org/pub/scm/linux/kernel/git/kabel/linux.git/log/?h=a3720-cpufreq-issues)

We've discovered a bug in Armada 3720 cpufreq driver that causes base CPU frequency to drop to 800 MHz on systems configured to 1 GHz. More info here:
https://www.spinics.net/lists/arm-kernel/msg844752.html

The patchset above led us to discover another bug, in the SOC itself, that causes the CPU to behave weirdly when frequency changes to 1 GHz. A similar erratum is documented by Marvell but only for systems where base frequency is 1.2 GHz.

We've discovered that to make cpufreq scaling stable on Armada 3720 on systems with base frequency 1 GHz, we also have to set voltage levels for L1, L2 and L3 loads to 1108 mV. (We were led to this by patch we found here
https://forum.armbian.com/topic/10429-how-to-make-espressobin-v7-stable/page/2/?tab=comments#comment-80012).

We would like you to build this sources and test the ondemand cpufreq governor on systems with variable CPU load, for at least 1 day (more is better). If you could also test the userspace governor and randomly change frequency, it would be great.

Please let me know if and when you are willing to do this.

Hi Marek,

Quoted 28 lines · Marek Behún

I have a request for testing some patches that fix cpufreq issues on Armada 3720 (EspressoBIN, uDPU, Devel Board, maybe others?).

It concerns top 4 commits of branch a3720-cpufreq-issues of repository
https://git.kernel.org/pub/scm/linux/kernel/git/kabel/linux.git/

(log at https://git.kernel.org/pub/scm/linux/kernel/git/kabel/linux.git/log/?h=a3720-cpufreq-issues)

We've discovered a bug in Armada 3720 cpufreq driver that causes base CPU frequency to drop to 800 MHz on systems configured to 1 GHz. More info here:
https://www.spinics.net/lists/arm-kernel/msg844752.html

The patchset above led us to discover another bug, in the SOC itself, that causes the CPU to behave weirdly when frequency changes to 1 GHz. A similar erratum is documented by Marvell but only for systems where base frequency is 1.2 GHz.

We've discovered that to make cpufreq scaling stable on Armada 3720 on systems with base frequency 1 GHz, we also have to set voltage levels for L1, L2 and L3 loads to 1108 mV. (We were led to this by patch we found here
https://forum.armbian.com/topic/10429-how-to-make-espressobin-v7-stable/page/2/?tab=comments#comment-80012).

We would like you to build this sources and test the ondemand cpufreq governor on systems with variable CPU load, for at least 1 day (more is better). If you could also test the userspace governor and randomly change frequency, it would be great.

Quoted 1 line

Please let me know if and when you are willing to do this.

Thanks for hunting this one down!

I've applied your 4 patches to v5.9 and gave it a quick spin.

I'm using schedutil, which had the very same issue. It never actually switched to 1000mhz. It claimed it did, but the mhz util as well as the 7z benchmark proved it never used anything >800mhz.

Before:

$ 7z b

7-Zip [64] 16.02 : Copyright (c) 1999-2016 Igor Pavlov : 2016-05-21

p7zip Version 16.02 (locale=en_US.UTF-8,Utf16=on,HugeFiles=on,64 bits,2 CPUs LE)

LE
CPU Freq: 793 793 794 793 794 792 793 794

RAM size: 985 MB, # CPU hardware threads: 2

RAM usage: 441 MB, # Benchmark threads: 2

Compressing | Decompressing

Dict Speed Usage R/U Rating | Speed Usage R/U Rating

KiB/s % MIPS MIPS | KiB/s % MIPS MIPS

22: 711 149 464 692 | 17501 194 770 1494

23: 708 155 465 722 | 17595 198 770 1523

24: 682 158 464 734 | 17079 196 764 1499

25:        663   160    473    757  |      15595   189    734   1388
----------------------------------  | ------------------------------
Avr:             156    466    726  |              194    760   1476

Tot: 175 613 1101

After:

$ 7z b

7-Zip [64] 16.02 : Copyright (c) 1999-2016 Igor Pavlov : 2016-05-21 p7zip Version 16.02 (locale=en_US.UTF-8,Utf16=on,HugeFiles=on,64 bits,2 CPUs LE)

LE
CPU Freq: 992 998 998 994 996 997 997 997

RAM size:     987 MB,  # CPU hardware threads:   2
RAM usage:    441 MB,  # Benchmark threads:      2

                       Compressing  |                  Decompressing
Dict     Speed Usage    R/U Rating  |      Speed Usage    R/U Rating
         KiB/s     %   MIPS   MIPS  |      KiB/s     %   MIPS   MIPS

22:        866   151    559    843  |      22334   198    962   1907
23:        872   152    584    889  |      21809   197    959   1888
24:        808   145    599    869  |      11413   110    915   1002
25:        716   137    596    819  |      21092   198    949   1877
----------------------------------  | ------------------------------
Avr:             146    585    855  |              176    946   1669

Tot: 161 765 1262

The measured frequency as well as the performance data finally looks good, so:

Tested-by Andre Heider <[email protected]>

Thanks,
Andre