osd3358 and "poweroff"

I have a custom board based on osd3358 and a little trouble getting the
"poweroff" command work as expected.

The device tree is almost the same as am335x-pocketbeagle.dts and I am running a v5.9-rc4 kernel.

&rtc {

is defined.

The board is powered through USB (haven't tried other options).

"poweroff" results in:

[info] Hardware Clock updated to Wed Sep 9 14:31:56 UTC 2020.
[ ok ] Deactivating swap...done.
[ 200.324307] EXT4-fs (mmcblk1p2): re-mounted. Opts: (null)
[info] Will now halt.
[ 202.548073] reboot: Power down

After that, the gpio-led showing cpu activity trigger goes off for a moment
but after that it is flickering as if there is still CPU activity with some
1 second modulation.

Pressing the reset button immediately reboots.

So this means that "poweroff" does not shut down the PMIC and the processor
is still idling.

Pressing the power button for 10 seconds does a forced shutdown and the
reset button is without significance.

And hints how to make "poweroff" work are welcome.

BR and thanks,
Nikolaus Schaller