Re: [PATCH 3/5] [pm] Respect the actual device power states in sysfs interface

Pavel Machek
2006-02-20T17:58:42Z

[-- Attachment #1: Type: text/plain, Size: 1201 bytes --]

Hi!

> > > > Compatibility is already restored.
> > >
> > > No, the interface is currently broken. The driver core does not
> > > dictate
> >
> > There were two different interfaces, one accepted 0 and 2, everything
> > else was invalid, and second accepted 0, 1, 2, 3.
> >
> > If you enter D2 on echo 2, you are breaking compatibility with 2.6.15
> > or something like that.
>
> I don't see how this is true. If a process writes "2" to a PCI device's
> state file, what else are sane things to do?

In some kernel version (2.6.15, iirc), device entered D3 if you wrote
"2" to state file, and there are programs out there that depend on
it. And there are some older programs that write "3" and expect D3. So
this interface really needs to die.

> You dropped the fundamental point, and I don't understand why you disagree
> with it - the driver core should not be dictating policy to the downstream
> drivers. It is currently doing this by filtering the power state that is
> passed in via the "state" file.

That's best we can do to stay compatible. Please introduce new file,
and make states string-based.
Pavel
--
Web maintainer for suspend.sf.net (www.sf.net/projects/suspend) wanted...