Re: [linux-pm] [RFC] Documentation for USB power management

On Mon, 8 Oct 2007, Oliver Neukum wrote:

> Am Samstag 06 Oktober 2007 schrieb Alan Stern:
> > +It is worth mentioning that many USB drivers don't support
> > +autosuspend.  In fact, at the time of this writing (Linux 2.6.23) the
> > +only drivers which do support it are the hub driver, kaweth, usblp,
> > +usblcd, usb-skeleton (which doesn't count), and usb-storage.  If a
> 
> Storage no longer does.
> You forgot the asix etherne driver.

I was working with an old -rc tree.  The appropriate changes will be 
made.

> > +Sometimes a driver needs to make sure that remote wakeup is enabled
> > +during autosuspend.  For example, there's not much point
> > +autosuspending a keyboard if the user can't cause the keyboard to do a
> > +remote wakeup by typing on it.  If the driver sets
> > +intf->needs_remote_wakeup to 1, the kernel won't autosuspend the
> > +device if remote wakeup isn't available or has been disabled through
> > +the power/wakeup attribute.
> 
> You should mention that a driver has to make sure that the device is
> awake for this to have immediate effect.

> > +External suspend calls should never be allowed to fail in this way,
> > +only autosuspend calls.  The driver can tell them apart by checking
> > +udev->auto_pm; this flag will be set to 1 for internal PM events
> 
> This is a bit unclear, as suspend methods are called with interface
> pointers. I think you need to elaborate.

Both good ideas, thank you.

Alan Stern


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