On Mon, Apr 03, 2017 at 09:51:32AM +0200, Zoltan Boszormenyi wrote:
> Use the common mutex from driver/usb/host/pci-quirks.c in the
> i2c-piix4 driver to synchronize access to the I/O port pair
> 0xcd6 / 0xcd7.
> 
> At the same time, remove the request_region() call to reserve
> these I/O ports, so the sp5100_tco watchdog driver can also
> load. The mutex is enough to protect the I/O port accesses.
> This is an old regression in Linux 4.4-rc4, caused by:
> 
> v2: Explicit extern reference for sb800_mutex
> 
> commit 2fee61d22e606fc99ade9079fda15fdee83ec33e
> Author: Christian Fetzer <fetzer.ch@gmail.com>
> Date:   Thu Nov 19 20:13:48 2015 +0100
> 
>     i2c: piix4: Add support for multiplexed main adapter in SB800
> 
> Signed-off-by: Zoltan Boszormenyi <zboszor@pr.hu>

Given the global mutex approach is accepted, the actual changes here
look okay to me. I'd really like a tag from Jean here, still. He is the
expert for this hardware which I barely know.