[Intel-gfx] i2c issue

[Eric Anholt]

I was looking at the mac mini patch queued to stable.  There are some
issues with how we're handling i2c bus setups.  Right now, it looks like
both CRT and SDVO will create an i2c bus for GPIOA.  Most of the driver
stuff is protected by our mutex, so two things won't hit the bus at the
same time, but there's also /sys/class/i2c-dev/*, which I expect we'll
see people making tools for at some point.  If we've got multiple i2c
devs using the same bus, then synchronization won't happen properly for
access through that interface, which doesn't take our mutex (but does
take an i2c mutex afaik).

The intel_i2c_create function should probably return a pointer to a
previously created i2c adapter for a GPIO.  To avoid refcounting
adventures, we could probably just free them all at unload time.

-- 
Eric Anholt
eric at anholt.net                         eric.anholt at intel.com


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