Re: [RFC Add in_use attribute] Let the driver know if it's in use

[Greg KH <greg@kroah.com>]

I seem to not have seen the original post about this, thanks Alan for
adding me to the cc:

On Mon, Apr 20, 2009 at 06:11:18PM -0400, Alan Stern wrote:
> On Mon, 20 Apr 2009, Rafael J. Wysocki wrote:
> 
> > On Thursday 16 April 2009, Michael Trimarchi wrote:
> > > Drivers on embedded systems would be smart enough
> > > to know that some of the devices should remain powered up, because
> > > they could still be useful even when the CPU wasn't running.
> > > The patch add the in_use attribute, that it can be used by the
> > > the drivers to avoid power down during suspend.

I'm confused, why would a driver not know if it was in use or not?
Actually, how would it not know already by virtue of what is happening
within it (io in flight, buttons being pushed, dma streaming, etc.)?

> > OK, so the idea is that in_use will be set by the user space for devices that
> > shouldn't be suspended.  Is this correct?

So userspace knows better than the kernel as to if a specific driver is
being used at the moment?  Why is this so?

confused,

greg k-h