[U-Boot] Commit "arm: kirkwood: configs: dreamplug: Convert to DM_SPI" breaks u-boot on Dreamplug

[Leigh Brown]

Hello,

Vagrant Cascadian asked for people to test the version of u-boot 
packaged
for Debian Buster.  I tested u-boot on my Dreamplug and found it was not
working correctly.  I raised a bug for Debian[1] but I have also tested
with the mainline version of u-boot and found the same issues.

This is the second issue that I found, and it causes u-boot to not 
detect
the SPI flash on the system.  I bisected the issue to the following 
commit:

commit 6aaf76beb131c2ff2b7184c2d63c2c63e5ab339c
Author: Chris Packham <judge.packham at gmail.com>
Date:   Wed Nov 21 22:22:23 2018 +1300

     arm: kirkwood: configs: dreamplug: Convert to DM_SPI

     Enable CONFIG_DM_SPI=y and CONFIG_DM_SPI_FLASH=y in the defconfig.

     Signed-off-by: Chris Packham <judge.packham at gmail.com>
     Reviewed-by: Stefan Roese <sr at denx.de>
     Signed-off-by: Stefan Roese <sr at denx.de>

The error manifests itself as follows:

U-Boot 2019.01+dfsg-1 (Jan 15 2019 - 00:36:19 +0000)
Marvell-DreamPlug

SoC:   Kirkwood 88F6281_A1
DRAM:  512 MiB
Loading Environment from SPI Flash... Invalid bus 0 (err=-19)
*** Warning - spi_flash_probe_bus_cs() failed, using default environment

A successful boot looks more like this:

U-Boot 2016.11+dfsg1-4 (Mar 27 2017 - 18:39:51 +0000)
Marvell-DreamPlug

SoC:   Kirkwood 88F6281_A1
SPI:   ready
DRAM:  512 MiB
WARNING: Caches not enabled
SF: Detected MX25L1605D with page size 256 Bytes, erase size 64 KiB, 
total 2 MiB

Unfortunately, I don't know where to start to diagnose the issue.  Could
anyone provide any pointers?  Happy to test any suggestions.

Regards,

Leigh.

--
[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=923379