Re: [patch update 3] PM: Introduce core framework for run-time PM of I/O devices

[Alan Stern <stern@rowland.harvard.edu>]

On Mon, 22 Jun 2009, Rafael J. Wysocki wrote:

> > And of course, synchronous pm_runtime_resume should always increment the 
> > counter.
> 
> Sure.

Now that I've thought about it some more, I decided that we might want
to be more flexible.  Without subjecting you to the entire line of
reasoning, let's just say that I'm starting to wonder whether it's such
a good idea to tie the counter increments to the PM core runtime resume
calls at all.

Maybe it would be better (easier to use, less constraining) to require
the runtime_resume callback to do its own pm_runtime_get.  That way the
driver would be entirely responsible for managing the usage counter;
the PM core wouldn't be involved.  pm_runtime_get would simply
increment the counter, so it could be used even in interrupt context.  
At the moment, I don't see any need for it to queue an autoresume
request if the device happens to be suspended.

Something like this was probably your intention all along.  :-)

Alan Stern