Am Dienstag, 17. November 2009 18:35:11 schrieb Adrian Taylor:
> Hi,
>
> Nokia S60 phones expose two CDC ACM channels. The first is a modem and
> is properly detected by the current cdc-acm driver. The second has a
> protocol ID of 0xff ('vendor specific') and /dev/ttyACM* is NOT
> currently created for it.
>
> This second channel is useful, since it's freely usable by third-party
> S60 application developers. It's sometimes used for debuggers or, in our
> case, remote control tools. At the S60 end, it just acts as a serial
> port (as it does on Windows and MacOS X). We should expose it as
> a /dev/ttyACM* device so that user-space tools can use it on Linux, too.
If it is a serial port, why not as a serial port /dev/ttyUSBx ?
> I attach a simple patch which does just that.
>
> However! It's not that simple.
>
> The reason is that some Windows Mobile/Windows CE devices support a
> remote ethernet protocol called RNDIS, which is build atop CDC ACM. This
> sadly uses the same class, subclass and protocol IDs.
>
> So currently drivers/net/usb/rndis_host.c tries to register for exactly
> the same devices. It eventually fails (when usbnet_generic_cdc_bind
Where is the problem?
> determines that it's not a suitable ethernet interface after all). But,
> if we create a serial port in cdc-acm, rndis_host doesn't even get a
> chance to try.
>
> What's the best way to allow each driver to have a crack at this
> particular interface?
>
> My plan would be:
> * No longer attempt to bind to this sort of interface from
> rndis_host.
How should this be possible? We must support real rndis devices.
> * Export a function from the rndis_host driver to request for it
> to try to bind to a particular interface.
> * Call that function from cdc-acm, for the relevant interfaces.
> * If it fails, fall back to exposing it as a tty device.
Absolutely no. We must support kernel configurations with only the
rndis host driver compiled.
> But this would introduce a dependency from cdc-acm on rndis_host, which
> doesn't sound right. Can anyone suggest a better way?
Please post "lsusb -v" for this device.
Regards
Oliver
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