Re: [PATCH] i2c/busses: Driver for Devantech USB-ISS I2C adapter

[Greg KH <greg@kroah.com>]

On Tue, Mar 22, 2011 at 09:25:07PM -0700, Guenter Roeck wrote:
> On Tue, Mar 22, 2011 at 11:45:24PM -0400, Greg KH wrote:
> > On Tue, Mar 22, 2011 at 08:43:47PM -0700, Guenter Roeck wrote:
> > > This patch adds support for the I2C interface of the Devantech USB-ISS
> > > Multifunction adapter.
> > > 
> > > Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
> > > ---
> > > The driver has one problem: It competes with the cdc_acm driver for device
> > > access. Copying the usb mailing list in the hope that someone can tell me
> > > if there is a way to prevent this from happening.
> > 
> > Why does it "compete"?
> > Is it because this driver also exposes a cdc-acm class interface?  Why
> 
> I guess so.
> 
> > is it doing that if it doesn't follow that spec?  We do already support
> 
> I don't know if it follows the cdc-acm specification or not, though I would
> think it does since the cdc-acm driver recognizes it. I do see the
> "This device cannot do calls on its own. It is not a modem." message.
> 
> I suspect the device exposes the cdc-acm class interface because it is
> a convenient means to make it show up as COM port in Windows.
> But I am not associated with the manufacturer, so that is just a wild guess.
> 
> If it does follow the cdc-acm specification, does that help me anything ?

It should, you can talk to the device from userspace using that virtual
serial port, right?  Isn't that what you need to do here?

Why try to create a new type of interface to the device from what it was
supposed to be by the manufacturer?

thanks,

greg k-h