Ax88172 vs FreeBSD USB stack

Bernd Walter ticso at
Fri Mar 28 14:05:42 PST 2003

On Fri, Mar 28, 2003 at 12:54:46PM -0800, Bill Paul wrote:
> > On Fri, Mar 28, 2003 at 11:16:55AM -0800, Maksim Yevmenkin wrote:
> > > Just FYI
> > > 
> > > ng_ubt(4) (/sys/netgraph/bluetooth/drivers/ubt) driver
> > > (Bluetooth USB devices) makes use of two interfaces.
> > 
> > >From a look into the driver these interfaces serve different
> > protocols.
> > I asume they are unrelated from a logical standpoint, but I don't
> > know bluetooth technology.
> > We have a similar situation with ulpt, where we usually have up
> > to three interfaces with different capabilities.
> > ulpt currently pics one of them, but we could also have three different
> > ulpt instances taking each one of them.
> The uplcom driver also uses two interfaces, but in that case, they
> put the interrupt endpoint on interface 0 and the bulk in/out endpoints
> on interface 1. When I saw that the AX88172 manual said that the device

My PL2303 has only one interface:
DEVICE addr 3
DEVICE descriptor:
bLength=18 bDescriptorType=device(1) bcdUSB=1.10 bDeviceClass=0 bDeviceSubClass=0
bDeviceProtocol=0 bMaxPacketSize=8 idVendor=0x067b idProduct=0x2303 bcdDevice=200
iManufacturer=0() iProduct=0() iSerialNumber=0() bNumConfigurations=1

CONFIGURATION descriptor 0:
bLength=9 bDescriptorType=config(2) wTotalLength=39 bNumInterface=1
bConfigurationValue=1 iConfiguration=0() bmAttributes=a0 bMaxPower=100 mA

INTERFACE descriptor 0:
bLength=9 bDescriptorType=interface(4) bInterfaceNumber=0 bAlternateSetting=0
bNumEndpoints=3 bInterfaceClass=255 bInterfaceSubClass=0
bInterfaceProtocol=0 iInterface=0()

ENDPOINT descriptor:
bLength=7 bDescriptorType=endpoint(5) bEndpointAddress=1-in
bmAttributes=interrupt wMaxPacketSize=10 bInterval=1

ENDPOINT descriptor:
bLength=7 bDescriptorType=endpoint(5) bEndpointAddress=2-out
bmAttributes=bulk wMaxPacketSize=64 bInterval=0

ENDPOINT descriptor:
bLength=7 bDescriptorType=endpoint(5) bEndpointAddress=3-in
bmAttributes=bulk wMaxPacketSize=64 bInterval=0

current configuration 1

Do you know which uplcom chip uses two interfaces?
It's interesting, because for the long run we really need to support
mutiple devices drivers for single devices and I don't want to break
support for such special devices.

> was supposed to have two interfaces, I wondered if maybe it had a
> similar setup, but I couldn't figure out how to access the second
> interface structure. For that matter, I didn't know for sure how to
> tell if it actually had one. (Sometimes manuals lie.) Hopefully when I
> try usbutils when I get home after work, I will learn more.

The number of interfaces is in the configuration descriptor.
After USB_ATTACH_START you should see it in uaa->nifaces.

> > Well the AC88172 PDF is very clear about having 2 interfaces.
> > The document also speaks about 4 endpoints, which I expect to be on
> > interface 0 as they also have listed endpoint number 0 - they don't
> > tell in the document.
> > What I currently don't know is why there are 2 interfaces.
> > The document also mentions some homenet capabilities on RJ11 - whatever
> > it means.
> The AX88172 supports both regular ethernet and HomePNA (ethernet
> over cat3 telephone wiring) transceivers. You don't need a second
> USB interface for this though: you send/receive packets the same
> way regardless of what kind of transceiver you have. (The ADMtek
> Pegasus (if_aue) supports the same feature and only uses one set
> of endpoints.)
> > Maybe it's an hardware optional interface, which is disabled in this
> > special device.
> > 
> > For the ID strings - it seems that the hardware vendor just left the
> > string empty in the eeprom.
> There is a UQ_NO_STRINGS quirk for this. Perhaps I should use it.

I asume it's only for devices that hang when asked.
I have an ulpt device without strings that works fine:
 port 2 addr 3: full speed, power 98 mA, config 1, product 0x0002(0x0002), vendor 0x3980(0x3980), rev 0.06
Well - transfered data corrupts sometimes, but I doubt it hast anything
to do with the strings.

B.Walter                   BWCT      
ticso at                                  info at

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