2010/9/9 Kay Sievers <kay.sievers@xxxxxxxx>:
> On Thu, Sep 9, 2010 at 11:21, Ludovic Rousseau
> <ludovic.rousseau@xxxxxxxxx> wrote:
>> I am trying to write a udev configuration file to change the group
>> ownership of the device if the device contains a CCID interface
>> (bInterfaceClass = 11 or 0x0B).
>>
>> I would like to use something like:
>> ATTR{bInterfaceClass}=="0b", GROUP="pcscd"
>> but that does not work.
>
> That not possible. Udev can only match on properties of the device
> ATTR or a parent device ATTRS.
>
> The device node you want to set the group to is the usb_device, but
> the match you want to do is on the usb_interface. At the moment the
> usb_device event is handled, the usb_interface does not exist, so this
> can never match. And from the usb_interface, which is a children and
> comes after the usb_device, you can not change the parent device node.
>
> Udev parses the usb descriptors and makes them available in a
> property. That's the only way to access usb_interface properties from
> the usb_device event.
>
> Something like:
> SUBSYSTEM=="usb", ENV{ID_USB_INTERFACES}="*:0b0000:*", GROUP= ...
> should do it.
Yes, it does work.
But I find the rule more obscure.
Since performance is not a critical point for me I think I will stay with:
ATTRS{bInterfaceClass}=="0b", RUN+="/bin/chgrp pcscd $root/$parent"
Thanks
--
Dr. Ludovic Rousseau
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