Re: [linux-usb-devel] Re: hotplugging to deal with firmware download

[Greg KH <greg@kroah.com>]

On Tue, Jun 04, 2002 at 12:26:31AM +0200, Oliver Neukum wrote:
> 
> > > > No, this should be done from userspace.
> > >
> > > Very well then, how ?
> > > I see no plan to do it with the present power management system.
> >
> > I agree.  That's why people are still working on the power management
> > system :)
> 
> Well, time is not infinite. I doubt the work'll be finished soon enough.

Heh, pessimist :)

> > > The devices are simply assumed to switch from suspended to working
> > > in kernel space. Suspended may mean off here.
> >
> > If "suspended" means off, then the device should start up in the powered
> > off state, and re-enumerate as a new usb device on powerup.
> 
> That exactly you cannot do. The result is file system corruption,
> interfaces assigned wrong adresses, cameras being switched.
> You need to retain device<->node correspondences.

Ok, let's state this right now then:
	If you have a USB device that needs firmware downloaded to it
	in order to work properly, do NOT mount any filesystems on that
	type of device and expect software suspend to work properly.  In
	fact, do not expect software suspend to work properly at all
	with these types of devices, and remove them before enabling
	software suspend.

Is that acceptable?

Does any other operating systems handle this any better?

> > If you _have_ to handle this today, then just leave the firmware within
> > the kernel driver, like all of the usb-serial devices have done :)
> >
> > If you wait a while, the rest of the power management sections of the
> > kernel will hopefully come together, allowing the various states of
> > shutdown to work properly, and be enumerated by _userspace_ tools.
> 
> Shutdown I don't worry about, resumption is anothere matter.

Resumption is part of the userspace solution too.

thanks,

greg k-h

_______________________________________________________________

Don't miss the 2002 Sprint PCS Application Developer's Conference
August 25-28 in Las Vegas -- http://devcon.sprintpcs.com/adp/index.cfm

_______________________________________________
Linux-hotplug-devel mailing list  http://linux-hotplug.sourceforge.net
Linux-hotplug-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel