On Sat, Jan 15, 2011 at 07:26:28PM +0100, José Félix Ontañón wrote:
> Hello everybody,
> I've got some doubts and problems getting USB class codes via udev and
> i'll be very grateful if someone could clarify.
>
> First of all, using udevadm i've realized some usb devices left the
> class/subclass/protocol attributes with 00:
>
> ATTR{bDeviceClass}=="00"
> ATTR{bDeviceSubClass}=="00"
> ATTR{bDeviceProtocol}=="00"
>
> Is that an issue on the usb device itself or an issue on udev reading
> usb device/interface descriptor?
No, that's normal, why wouldn't it be? Those attributes are properly
defined for these devices in the interface values for those fields, not
the main device values.
> Second, i've some doubts about when should I use the
> ID_USB_INTERFACES, TYPE or INTERFACE property: in which cases should I
> use one or another? Why the TYPE property sometimes appear as 0/0/0
> even when the ID_USB_INTERFACES and INTERFACE properties are filled?
That's normal, and to be expected. Please read the usb.org specs for
details if you really are curious.
thanks,
greg k-h
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