Booting RPi4 from USB MSD by 5.10

[Ryutaroh Matsumoto]

Hi all,

Just FYI, CONFIG_RESET_RASPBERRYPI=y seems necessary
when RPi4 is booted from USB MSD by the upstream kernel 5.10.x
and CONFIG_USB_XHCI_PCI=m.
CONFIG_RESET_RASPBERRYPI=m is insufficient.

When RPi4 is booted from an SD card,
CONFIG_RESET_RASPBERRYPI=m
also works well.
Related info: https://salsa.debian.org/kernel-team/linux/-/merge_requests/315

By the way, when 5.10 kernel is booted from USB MSD and udisks2 is
installed, kernel emits flood of false media change messages to udev,
and almost 100% of CPU usage is consumed by udev, dbus and udisks2
combined. I wonder if anyone other than me has experienced the same issue.
Bug report was filed to Debian as
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=980980

Best regads, Ryutaroh Matsumoto