On 4 Jun 2003 at 19:29, Oliver Neukum wrote:

> 
> > > As for cdc-acm, I don't think it should be doing that.  The code
> > > that chooses a configuration can reasonably change its mind, for
> > > example if there was a choice and no driver could bind to that
> > > initial selection ... I don't think probe() should be allowed to
> > > change configurations.
> >
> > To the contrary, probe() is the only component in the system that
> > actually understands a device configuration.  The higher-level code
> > is just blindly flipping through a list looking for help.
> >
> > The driver is the component that understands the attached device and
> > should be able to determine its configuration.  That's the
> > definition of a driver, IMHO.
> 
> A device may have several interfaces in its configurations. Which
> driver shall decide? And who shall decide which driver is to decide?
> 
> But of course there may be vendor specific devices whose drivers
> should set configuration. We need to accomodate both. The question is,
> how exactly?
> 
>  Regards
>   Oliver

The only information the core has is the vendor and product IDs.  
This is certainly not sufficient to determine which of multiple 
configurations should be used / activated.

It is the responsibility of the driver to take control of a device if 
it can, including multiple dissimilar internal functions.  Since it 
was registered with a matching vendor and product ID in the first 
place, it can presumably handle all aspects of that device.

A good example is my Brother MFC 9200C.  It contains a printer, a fax 
machine, a scanner, and a smart-card reader.  Each of these has 
different driver requirements, yet they should all be supported (or 
not support) by a single driver and a single probe() call.  IMHO.

Regards,

Leigh Bassett




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