[Intel-gfx] [RFC 1/4] x86/platform/intel/iosf_mbi: Add a mutex for punit access

Jarkko Nikula jarkko.nikula at linux.intel.com
Fri Jan 13 10:34:54 UTC 2017

On 01/13/2017 11:26 AM, Ville Syrjälä wrote:
> It also feels quite hand wavy since the punit could do whatever at
> any time AFAIK. Eg. if there's some thermal event or something the
> punit might kick into action. So trying to protect this from the OS
> side might not be able to avoid these problems entirely. It feels like
> there really should be some kind of shared hardware/firmware mutex
> with the punit to arbitrate access to the i2c bus.
There is an HW semaphore for I2C access. It is implemented in 
drivers/i2c/busses/i2c-designware-baytrail.c and another set from Hans 
is adding support for Cherrytrail into it.


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