Thread (5 messages) 5 messages, 4 authors, 2011-02-05

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

From: Rajendra Nayak <hidden>
Date: 2011-01-31 15:28:29
Also in: linux-arm-kernel, linux-omap

-----Original Message-----
From: Alan Stern [mailto:stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org]
Sent: Monday, January 31, 2011 8:43 PM
To: Rajendra Nayak
Cc: Kevin Hilman; Ben Dooks; linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org;
linux-pm-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org; linux-
omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [linux-pm] [PATCH] i2c: OMAP: fix static suspend vs.
runtime suspend
On Mon, 31 Jan 2011, Rajendra Nayak wrote:
quoted
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.
Thanks, I did remember seeing the pm_runtime_get_noresume()
in dpm_prepare(). Just did not correlate it was the same Kevin
was trying to say.

Regards,
Rajendra
Alan Stern
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