usb/131123: [patch] re-add UQ_ASSUME_CM_OVER_DATA USB quirk

[Rudolf Cejka]

linimon at FreeBSD.org wrote (2009/01/30):
>  The sc_cm_over_data flag is never checked elsewhere.  Are you saying
>  that the umodem_set_comm_feature() causes the problem?

Yes, I can imagine three possible reasons:

1) There is not any bug in umodem_set_comm_feature(), but the device
   would be buggy and could not accept requested settings, which
   I suppose are according to the specifications.

2) There is some bug in umodem_set_comm_feature().

3) It seems, that the device does not survive two configuration settings,
   however I do not understand which. See Linux discussion about this device
   https://kerneltrap.org/mailarchive/linux-usb-devel/2007/10/27/361160/thread
   and Matthias Fuchs: ... I found out that the 2.4 kernels send two
   'set configuration' requests to the USB modem. Either this is not
   allowed or the modem's firmware does not like this. After the 2nd set
   configuration request the device disconnects...
   Maybe FreeBSD had the same problem and configuration settings are
   performed in another place too.

If you are interested, I can do any software tests you need or want
to do, so that you can really understand what happens.

In all events, MC75/ES75 immediately disconnects and resets. Attempts
are repeated every 10 seconds (Unknown USB device is written by devd,
I do not know why - but after patch it disappears):

...
Jan 28 18:14:00 kernel: ucom0: detached

Jan 28 18:14:09 root: Unknown USB device: vendor 0x0681 product 0x0034 bus uhub0
Jan 28 18:14:09 kernel: ucom0: <Siemens AG Wireless Modules MC75, class 2/0, rev 1.10/0.00, addr 2> on uhub0
Jan 28 18:14:09 kernel: ucom0: iclass 2/2
Jan 28 18:14:09 kernel: ucom0: data interface 1, has CM over data, has no break
Jan 28 18:14:09 kernel: ucom0: status change notification available
Jan 28 18:14:09 kernel: ucom0: at uhub0 port 1 (addr 2) disconnected
Jan 28 18:14:09 kernel: ucom0: detached

Jan 28 18:14:20 root: Unknown USB device: vendor 0x0681 product 0x0034 bus uhub0
...

-- 
Rudolf Cejka <cejkar at fit.vutbr.cz> http://www.fit.vutbr.cz/~cejkar
Brno University of Technology, Faculty of Information Technology
Bozetechova 2, 612 66  Brno, Czech Republic