Re: [RFC][PATCH] Power domains for platform bus type

From: Alan Stern
Date: Sun Jan 30 2011 - 11:03:40 EST

On Sun, 30 Jan 2011, Rafael J. Wysocki wrote:

> Hi,
> This is something we discussed during the last Linux Plumbers Conference.
> The problem appears to be that the same device may be used in different
> systems in different configurations such that actions necessary for the
> device's power management can vary from one system to another. In those
> cases the drivers' power management callbacks are generally not sufficient,
> because they can't take the configuration of the whole system into account.
> I think this issue may be addressed by adding objects that will represent
> power domains and will provide power management callbacks to be executed
> in addition to the device driver's PM callbacks, which is done by the patch
> below.
> Please have a look at it and tell me what you think.

One thing about this implementation is slightly questionable. The new
power_domain callbacks were added to the __weak platform PM routines,
which means they will have to be included in every overriding routine
provided by a platform imiplementation.

Would it be better to separate these things? Have the power_domain
callbacks occur in a static outer function which then calls a public
__weak inner function that can be overridden?

Alan Stern

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