Re: [RFD] How to tell ACPI drivers what the target sleep state is (was: Re: [PATCH 1/2] acpi choose sleep state help)

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Thursday, 21 June 2007 17:37, David Brownell wrote:
> 
> > > IMO it can be done in two different ways:
> > > 1) via a .suspend() argument
> > > 2) via a global variable that the drivers can read.
> 
> For sufficiently small values of "two" that is.  
> 
> Other solutions that have been described on the PM list include
> 
>   3) Providing accessors to the information actually needed
>      in drivers ... e.g. say whether this clock or power domain
>      will be available in that target state.

Well, you need to store that information somewhere.  The way in which
it will be provided to drivers is a secondary thing.

To me, the most important question is whether we want to pass that information
as a .suspend() argument or in any different way, which involves the use of a
global variable (or a set of variables) and that's 2).

>   4) Act more like "current" ... there's a function returning
>      whatever "state" struct is settled on.  (But ideally
>      without the pseudo-global.)

How would you be going to arrange that in practice?

> I'm amused that nobody really reacted to the technical comments in
> my previous posts on this thread.  That's unfortunate, since from
> where I sit it feels to me like everyone else is a johnny-come-lately
> on this issue, and is now grasping at the quickest and dirtiest ways
> to work around the issue instead of coming to grasp with the various
> underlying issues.
> 
> IMO #3 is strongly preferable.

Of course we can do that.  At least I don't have any objections.

Greetings,
Rafael


-- 
"Premature optimization is the root of all evil." - Donald Knuth