From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jim Paris <jim@jtan.com>
Date: Thu, 31 Jul 2008 17:13:23 +0000
Subject: Re: uDev - multiple of same device
Message-Id: <20080731171323.GA22057@jim.sh>
List-Id: <linux-hotplug.vger.kernel.org>
References: <5652842e0807310943s2666ada8h5202232847a42481@mail.gmail.com>
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To: linux-hotplug@vger.kernel.org

Hi Chris,

> I've noted that the 7-port hub I am using to connect everything is
> simply 2 4-port hubs chained together. As such, I am able to use the
> LEVEL= directive to distinguish between the ports on the first hub vs.
> the second hub. However, using udevinfo, I have not found a unique and
> constant SYSFS attribute that allows further granularity.

$ udevinfo --attribute-walk --name=/dev/input/mouse1  | grep phys
    ATTRS{phys}="usb-0000:00:1a.7-3.2.4/input0"

That's the physical address for the device.  The 3.2.4 indicates
that you're on port 3 of the root hub, then port 2 of the first hub,
and port 4 of the second hub.

You could also just use the existing /dev/input/by-path links, which
are similar.

> I know that
> I can get port information from /proc/bus/usb/devices, but I still run
> into the problem of not having
> a SYSFS attribute (or some other uDev directive) to cross reference
> with that information.

If you want info from /proc/bus/usb/devices, you could have udev run a
script and have that script output variables that udev can use for
matching.

-jim