Re: Why USB must be so hard to use ?

On Fri, Sep 21, 2007 at 10:38:29AM -0700, Luigi Rizzo wrote:
i recently tried to attach one of the Openbeacon USB devices

http://wiki.openbeacon.org/wiki/OpenBeacon_USB

to a -stable box, and "of course" attach failed, even though the
same thing is claimed to work right away on Linux and XP without
any special driver.

It wasn't too hard to convince umodem.c to attach to the device,
but i had to put the <vendor,product> ids in the list of devices
explicitly recognised, and further disable the extra check for
capabilities at the end of umodem.c::USB_MATCH (or umodem_match in
-current). The device itself returns a class UICLASS_CDC, but
subclass and protocol are 0, i.e. this is a very basic serial device
as probably many gadget we are going to see in the future.

Since it's using an Atmel ARM.
I had to create the following umodem patch to get a pseudo serial
port for accessing the sam-ba CDC for flashing the controller:
Index: umodem.c
===================================================================
RCS file: /home/ncvs/src/sys/dev/usb/umodem.c,v
retrieving revision 1.57
diff -u -r1.57 umodem.c
--- umodem.c 31 Jan 2005 13:58:10 -0000 1.57
+++ umodem.c 20 Aug 2006 17:05:34 -0000
@@ -256,6 +260,15 @@
id->bInterfaceProtocol == UIPROTO_CDC_AT)
ret = UMATCH_IFACECLASS_IFACESUBCLASS_IFACEPROTO;

+#if 1
+ if (ret == UMATCH_NONE &&
+ id->bInterfaceClass == UICLASS_CDC_DATA &&
+ id->bInterfaceSubClass == UISUBCLASS_DATA &&
+ id->bInterfaceProtocol == 0x00)
+ ret = UMATCH_IFACECLASS_IFACESUBCLASS_IFACEPROTO;
+ return ret;
+#endif
+
if (ret == UMATCH_NONE)
return (ret);

I was told that it just works under Linux and Windows has such
a generic driver as well.
But the sam-ba firmware in the AT91SAM7X256 wasn't able to build
a tty under Mac OS X as well.
We should really have a generic CDC tty driver, since it is used
very often for simple USB projects.

--
B.Walter http://www.bwct.de http://www.fizon.de
bernd@xxxxxxx info@xxxxxxx support@xxxxxxxx
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