Re: Raspberry Pi POE+ hat overlay

On May 18, 2023, at 01:29, Nuno Teixeira <eduardo@freebsd.org> wrote:

> Confirmed that arm_boost is enable by default on rpi4 rev >= 1.4 as I checked with htop.
> 
> Also, tested arm_freq=1800 and it crashes FreeBSD around initializing console/video and detecting mouse.

Overclocking by setting the arm_freq directly involves also
managing over_voltage explicitly, such as:

over_voltage=6

A sequence I use (and have used for a long time) is:

[pi4]
over_voltage=6
arm_freq=2000
sdram_freq_min=3200
force_turbo=1

But each RPi4B has heatsinks, a case with a fan,
and a power supply rated for 5.1V 3.5A (so: has
some extra margin).

But the range of RPi4B's span Rev 1.1, Rev 1.4,
and Rev 1.5, a mix of 4 GiByte RAM and 8 GiByte
RAM models. All use those settings.

As I understand, arm_boost implicitly does the
extra things required for its implicit frequency,
unlike assigning arm_freq or the like.

If force_turbo is not used, it can be that:

#
# Local addition that avoids USB3 SSD boot failures that look like:
#   uhub_reattach_port: port ? reset failed, error=USB_ERR_TIMEOUT
#   uhub_reattach_port: device problem (USB_ERR_TIMEOUT), disabling port ?
initial_turbo=60

is required for USB based booting. But this also
gets into if the notation is supported or not for
the firmware vintage used.

The initial_turbo use happens to avoid frequency
variability during boot and it appears that FreeBSD
does not necessarily tolerate such variability in
that time frame.

Also: I happen to have USB3 boot media for which use
of usb_pgood_delay=2000 is sufficient but without
some such in/for U-Boot, U-Boot has problems
recognizing the device (before FreeBSD is even
involved). I build the U-Boot port with the
assignment built in.

> As linux config.txt says:
> ---
> [pi4]
> # Run as fast as firmware / board allows
> arm_boost=1
> ---
> firmware must be updated to support this feature for sure.

I'm not aware of a dated list of when the various
config.txt notations were first supported (firmware
version). This makes it messier to use the web's
published information, if one is using the firmware
vintage that FreeBSD has in its port for the
firmware.

The notation that I use has been around for a long
time.

> Cheers,
> 
> Nuno Teixeira <eduardo@freebsd.org> escreveu no dia quarta, 17/05/2023 à(s) 14:08:
> (...)
> 
> I was meant using 13.2 not 12.3 :)
> 
> Doug Rabson <dfr@rabson.org> escreveu no dia quarta, 17/05/2023 à(s) 13:47:
> I'm not sure about 12.3 either - you could try with 13.2 and see if that makes a difference.
> 
> On Wed, 17 May 2023 at 13:45, Nuno Teixeira <eduardo@freebsd.org> wrote:
> Hey,
> 
> Ok. I'm new to rpi4 and arm in general but tomorrow I will force 'arm_freq=1800' again just to see it it crashes again.
> I will check too what values linux shows.
> 
> I don't know if firmware/uboot version included in 12.3 supports this feature.
> 
> Cheers,
> 
> Doug Rabson <dfr@rabson.org> escreveu no dia quarta, 17/05/2023 à(s) 13:11:
> Hi Nuno,
> 
> I'm not sure where to start - I just happened to notice in the documentation here: https://www.raspberrypi.com/documentation/computers/config_txt.html that the cpu frequency Pi4B R1.4 was listed as 1800 if arm_boot=1 so I tried it.
> 
> Doug.
> 
> 
> 
> On Wed, 17 May 2023 at 11:11, Nuno Teixeira <eduardo@freebsd.org> wrote:
> Hello Doug,
> 
> I have too a 1.5 rpi but arm_boost=1 isn't doing anything, htop shows 1500Mhz when doing something intensive.
> I'm running 13.2 stable
> 
> Do I missing something?
> 
> Could you take a look at my setup?
> 
> Thanks,
> 
> Doug Rabson <dfr@rabson.org> escreveu no dia terça, 16/05/2023 à(s) 17:19:
> 
> On Sat, 13 May 2023 at 13:45, Doug Rabson <dfr@rabson.org> wrote:
> I was able to build an updated rpi-firmware port based on 1.20210805 and this boots successfully on pi400 as well as rpi4. With this, I can load the rpi-poe-plus overlay and I just need to try and reverse engineer the undocumented mailbox API by reading the Linux code.
> 
> I have a first approximation of a fan driver which works with the 1.20210805 firmware (actually, I substituted rpi-poe-plus.dtbo from 1.20210831 which just changes the fan levels for the POE+). I'm testing with an rpi4B rev 1.5 with 'make -j4 buildworld' and the fan is keeping the cpu temperature below 65 degrees which is nice, especially since I set arm_boost=1 in config.txt which boosts the cpu frequency up to 1800 for this board.
> 
> Does anyone have a pointer to the problem with firmware later than 20210805? Would it make any kind of sense to try to get the fix into releng/13.2 as an errata?
> 


===
Mark Millard
marklmi at yahoo.com