MTK mt8173-evb: mainline unstable, and big-endian boot failures

[Kevin Hilman]

Kevin Hilman <khilman at baylibre.com> writes:

[...]

> It seems to be pretty stable up through v4.4 but
> unreliable/unpredictable in v4.5-rc1 and lots of places in between.
> It's hard to bisect because it doesn't reliably fail, but when it does
> fail to finish booting, it's typically after it reaches a shell, and
> trying to run various simple shell commands fails to complete, like
> this example from next-20160125[2].
>
> To me this suggests possibly an issue with the idle driver where
> characters might be getting lost on the serial console, which causes
> the automated boot scripts to fail because the shell is still waiting
> for the command to be finished.

FWIW, I think I confirmed my suspicion that it's an idle driver issue
because adding 'nohlt' on the cmdline, which forces cpuidle_poll mode
(essentially disabling cpuidle) makes mainline boot quite reliably on my
mt8173-evb board now.

Kevin