Commit "spi: rockchip: set higher io driver when sclk higher than 24MHz" causes kernel panic

[jakob-tsd]

This commit

commit 7e4349ec9d70dbcfe7f78125700d2685539ea1bd
Author: Huibin Hong <huibin.hong@rock-chips.com>
Date:   Sat Feb 24 20:57:22 2018 +0800

    spi: rockchip: set higher io driver when sclk higher than 24MHz

    Change-Id: I963c92eab7f7bff0b32e2ac262aa79f0667f39ee
    Signed-off-by: Huibin Hong <huibin.hong@rock-chips.com>

causes this upon booting our RK3399-Q7 module:

[    2.714032] rockchip-spi ff1d0000.spi: no high_speed pinctrl state
[    2.721431] Unable to handle kernel NULL pointer dereference at virtual address 00000005
...
[    6.530910] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b

Full dmesg: https://gist.github.com/jakob-tsd/b4618812b4d2b4ba78d5133bfab2844d
Stack trace: https://gist.github.com/jakob-tsd/bf3bed809df4558fde37de9864e18689
(with line numbers)

I have reverted the commit in our tree and it fixes the problem. So this is not urgent or anything but may be something to consider when you next touch the spi code.

[ayufan]

FYI: #78