Re: [linux-pm] suspend blockers & Android integration

From: Alan Stern
Date: Fri Jun 11 2010 - 16:48:21 EST

On Fri, 11 Jun 2010, Mark Brown wrote:

> On Fri, Jun 11, 2010 at 10:46:27AM -0400, Alan Stern wrote:
> > On Fri, 11 Jun 2010, James Bottomley wrote:
> > > The one thing that does look difficult is that these power constraints
> > > are device (and sometimes SoC) specific. Expressing them in a generic
> > > way for the cpu govenors to make sense of might be hard.
> > Doesn't the clock framework already handle this sort of thing?
> The clock framework is implemented independantly for each CPU.

That's not an impediment, since drivers' requirements regarding which
clocks remain running in which power states are necessarily
platform-dependent also.

On Fri, 11 Jun 2010, James Bottomley wrote:

> Well, there are two elements to "this sort of thing":
> 1. Allow a driver to request that a given clock not be turned off.
> 2. Make the cpuidle governors aware of a pending "don't turn off X
> clock source" so they can keep the system in a state where the
> clock doesn't get powered down.
> As far as I can tell from the code, neither currently exists at the
> moment.

Well then, can (or should) the clock framework interact with the
pm-qos subsystem so that drivers don't have to worry about it?

Alan Stern

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