[linux-pm] [PATCH] i2c: OMAP: fix static suspend vs. runtime suspend

Alan Stern stern at rowland.harvard.edu
Mon Jan 31 10:13:13 EST 2011

On Mon, 31 Jan 2011, Rajendra Nayak wrote:

> Can you elaborate a bit more on how/why runtime PM transitions
> are disabled during system suspend, and how is it taken care
> of that a runtime resume of a device works however a subsequent
> runtime (re)suspend does not?

I'll answer for Kevin.  This is done by the PM core, in order to 
prevent runtime power transitions from interfering with a system power 
transition.  The PM core increments the device's usage_count; this 
prevents the device from being runtime-suspended but it allows 
runtime-resume calls to go through.

Alan Stern

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