beaglebone black boot failure Linux v5.15.rc1

["Vaittinen, Matti" <Matti.Vaittinen@fi.rohmeurope.com>]

Hi dee Ho peeps,

Yesterday I asked about this at #armlinux so if someone saw my message 
there - this is the same topic.

My beaglebone black (rev c) based test environment fails to boot with 
v5.15-rc1. Boot succeeds with the v5.14.

I use pretty old uBoot, TFTP to load kernel and device-tree, and have 
hosted the rootfs on NFS server.

The v5.15-rc1 fails to boot with no prints from kernel visible in serial 
console. Please see the serial log at the end of this message.

Bisecting the Linus' tree pointed out the commit:
[1c7ba565e70365763ea780666a3eee679344b962] ARM: dts: am335x-baltos: 
switch to new cpsw switch drv

I don't see this exact commit touching the BBB device-tree. In Linus' 
tree it is a part of a merge commit. Reverting the whole merge on top of 
the v5.15-rc1

This reverts commit 81b6a285737700c2e04ef0893617b80481b6b4b7, reversing
changes made to f73979109bc11a0ed26b6deeb403fb5d05676ffc.

makes my beaglebone black to boot again.

Yesterday I tried adding this patch:
https://lore.kernel.org/linux-omap/20210915065032.45013-1-tony@atomide.com/T/#u
pointed by Tom on top of the v5.15-rc1 - no avail. I also did #define 
DEBUG at ti-sys.c as was suggested by Tom - but I don't see any more output.


Any suggestions what to check next?

Best Regards
	Matti Vaittinen


Serial log below:

Reset Source: Global external warm reset has occurred.
Reset Source: Power-on reset has occurred.
MMC:   OMAP SD/MMC: 0, OMAP SD/MMC: 1
Using default environment

Net:   <ethaddr> not set. Validating first E-fuse MAC
cpsw, usb_ether
Press SPACE to abort autoboot in 2 seconds
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
gpio: pin 56 (gpio 56) value is 0
gpio: pin 55 (gpio 55) value is 0
gpio: pin 54 (gpio 54) value is 0
gpio: pin 53 (gpio 53) value is 1
switch to partitions #0, OK
mmc0 is current device
gpio: pin 54 (gpio 54) value is 1
Checking for: /uEnv.txt ...
reading uEnv.txt
561 bytes read in 4 ms (136.7 KiB/s)
gpio: pin 55 (gpio 55) value is 1
Loaded environment from uEnv.txt
Importing environment from mmc ...
Checking if uenvcmd is set ...
gpio: pin 56 (gpio 56) value is 1
Running uenvcmd ...
link up on port 0, speed 100, full duplex
Using cpsw device
TFTP from server 192.168.255.126; our IP address is 192.168.255.1
Filename 'zImage'.
Load address: 0x81000000
Loading: #################################################################
          #################################################################
          #################################################################
          #################################################################
          #################################################################
          #################################################################
          #################################################################
          #################################################################
          #################################################################
          #################################################################
          #######################
          4.5 MiB/s
done
Bytes transferred = 9875968 (96b200 hex)
link up on port 0, speed 100, full duplex
Using cpsw device
TFTP from server 192.168.255.126; our IP address is 192.168.255.1
Filename 'am335x-boneblack.dtb'.
Load address: 0x82000000
Loading: #####
          3.2 MiB/s
done
Bytes transferred = 67151 (1064f hex)
Kernel image @ 0x81000000 [ 0x000000 - 0x96b200 ]
## Flattened Device Tree blob at 82000000
    Booting using the fdt blob at 0x82000000
    Loading Device Tree to 8ffec000, end 8ffff64e ... OK

Starting kernel ...