[Intel-gfx] [PATCH v2 4/5] i2c: designware-baytrail: Force the CPU to C1 state while holding the punit semaphore

[Andy Shevchenko]

On Sat, 2016-12-31 at 22:29 +0100, Hans de Goede wrote:

> This makes sense, the iosf_mbi code which is used by the
> i2c bus semaphore code has this:
> 
> arch/x86/platform/intel/iosf_mbi.c:
> 
> int iosf_mbi_read(u8 port, u8 opcode, u32 offset, u32 *mdr)
> {
>          u32 mcr, mcrx;
>          unsigned long flags;
>          int ret;
> 
>          /* Access to the GFX unit is handled by GPU code */
>          if (port == BT_MBI_UNIT_GFX) {
>                  WARN_ON(1);
>                  return -EPERM;
>          }
> 
> 	...
> }
> 
> So the i915 driver definitely is interacting with the punit
> through the mailbox interface too...

Yes, they have private mailbox support. Once I talked to Ville to make
at least definitions common between two: iosf_mbi.h and whatever i915 is
using, but have no time to implement that.

-- 
Andy Shevchenko <andriy.shevchenko at linux.intel.com>
Intel Finland Oy