Just a heads-up to avoid more people lose hours in debugging:
After upgrading from 4.9 to 4.14 I noticed USB support was broken on
my Allwinner A20 boards like Cubietruck and first generation BananaPi.
There is simply no output of the lsusb command, and subsequently no
connected USB devices are detected.
Bisecting led to
commit 6254a6a94489c4be717f757bec7d3a372cba1b6e
Author: Arnd Bergmann <arnd@xxxxxxxx>
Date: Thu Apr 27 21:11:48 2017 +0200
power: supply: axp20x_usb_power: add IIO dependency
which already happened in the 4.12 development. Turns out after that
commit "make oldconfig" will silently drop CONFIG_AXP20X_POWER unless
CONFIG_IIO is set - but CONFIG_AXP20X_POWER is needed for USB on these
boards.
Solution: Enable CONFIG_IIO, but no particular driver is required. I'm
not aware whether it's possible to provide a smoother upgrade path in
Kconfig, "selects" instead of "depends" might have been an option.
Christoph, two more 4.14 regressions to go