Re: Re: [RFC] Implementation of SCSI dynamic power management

On Tue, 8 Jan 2008, Pavel Machek wrote:

quoted

In fact suspend methods already do take an argument specifying the
reason they were called.  It wouldn't be hard to add a couple of extra 
PM_EVENT_* values for manual suspend and autosuspend.  The problem is 
that resume methods don't take a corresponding argument.

Well, you could store the value in struct device or something.

There's other problem: if autosuspend is != NULL, you know device
supports autosuspend.

If you call existing suspend(PMSG_AUTOSUSPEND), and driver does not
support it, it will crash and burn.

That's right.  The problem doesn't arise in SCSI because there only the
sd driver supports suspend at all -- and now it supports autosuspend as
well.  In USB I had to add an extra "supports_autosuspend" bitflag to
the usb_driver structure.

Alan Stern