Re: [linux-usb-devel] Re: usb sysfs intf files no longer createdwhen probe fails

From: Alan Stern
Date: Wed Jun 22 2005 - 10:50:59 EST

On Wed, 22 Jun 2005, Stelian Pop wrote:

> Le mercredi 22 juin 2005 à 07:59 -0700, Greg KH a écrit :
> > On Wed, Jun 22, 2005 at 03:50:56PM +0200, Stelian Pop wrote:
> > > I use the 'atp' input driver from to drive this
> > > touchpad. When removing the driver I also get an oops, possibly related
> > > to the previous failure to create the sysfs file:
> >
> > Sounds like a bug in that driver, care to ask the authors of it about
> > this?
> I am the author :)
> That driver worked until yesterday, and I was not able to find out about
> any API change which would disrupt it now, that's why I reported this to
> the list...

This is a curious aspect of the driver model core. Should failure of a
driver to bind be considered serious enough to cause device_add to fail?
The current answer is Yes unless the driver's probe routine returns
-ENODEV or -ENXIO, in which case the failure is not considered serious.

IMO this is a perverse way of doing things. The existence of a device has
nothing to do with what driver is bound to it. Either the device exists
or it doesn't -- and if it exists, failure to bind a driver shouldn't
prevent adding the device into sysfs. Right now, however, it does.

Alan Stern

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