Re: [linux-pm] Re: The evilness of struct usb_device->auto_pm

Pavel Machek <[email protected]>
Newsgroups gmane.linux.usb.devel
Message-ID <[email protected]>
Hi!

> > > That's because the notifications go up the device tree, not down.  When 
> > > a child is suspended, the parent is notified.  Then if the driver sees 
> > > that all the children are suspended, the parent can be suspended as 
> > > well.
> > > 
> > > Oliver has been trying to subvert this model by making usb-storage 
> > > responsible for suspending the SCSI disk and CD/DVD drivers, which are 
> > > located beneath it in the device tree.  I've been trying to convince 
> > > him that the proper way to handle things is to let the SCSI drivers 
> > > decide for themselves when their devices can be suspended, and then 
> > > have them inform usb-storage.
> > 
> > Yes, I think that the SCSI layer should decide.
> > 
> > I guess that the SCSI layer is not really autosuspend-aware, is it?
> 
> Not yet.  I would like it to become autosuspend-aware.  Oliver wants to
> avoid that by keeping all the awareness in usb-storage.  (But then what
> about all the other SCSI host-adapter drivers?  Will they each have
> their own way of deciding when a SCSI device can be suspended?)

I think I'd prefer to have autosuspending in SCSI layer. That way, we
should be able to handle automatic disk spindowns nicely...
							Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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