u-boot debug, was: Re: U-boot on RPI3, sees disk but won't boot it

From: bob prohaska <fbsd_at_www.zefox.net>
Date: Sun, 25 Sep 2022 16:05:31 UTC
On Wed, Sep 21, 2022 at 06:45:00PM -0700, bob prohaska wrote:
> After setting initial_turbo=60 in config.txt the first reboot
> found the disk, the second did not. Running usb reset then
> found the disk, but run bootcmd_usb0 seemingly caused a reset
> that  _then_ found the disk. 

It looks as if u-boot is somehow restarting itself unexpectedly.
This is an RPi3B running stable-13, system and ports up to date
as of yesterday.

Here's an example session following a failed boot attempt:

U-Boot> usb reset
resetting USB...
Bus usb@7e980000: USB DWC2
scanning bus usb@7e980000 for devices... 6 USB Device(s) found
       scanning usb for storage devices... 1 Storage Device(s) found
U-Boot> usb part

[I think some information about the disk should have been displayed]

U-Boot 2022.04 (Sep 23 2022 - 17:28:32 -0700)

DRAM:  948 MiB

[...usual startup output]

Are there any debug switches for u-boot? I've looked a bit and
what I find is either stale or not implemented. There's a reference
to a "log" command, but it does not seem to be recognized.

It does seem clear that the presence of a timeout file makes no
meaningful difference. Boot succeeds rate is less than 50%

This is using an unmodified u-boot-rpi-arm64 built locally. The
system has no microSD installed, u-boot is started from the USB
disk (which is found by firmware without trouble). 

If setting up a microSD to start u-boot alone would simplify 
matters that seems worth a try. Hints much appreciated! 

Once the machine boots into freebsd it seems to work just fine.
The problem appears to be with u-boot only.

Thanks for reading,

bob prohaska