From mboxrd@z Thu Jan  1 00:00:00 1970
From: Frank Praznik <frank.praznik@oh.rr.com>
Subject: Re: [PATCH 0/6] HID: Add a stable method for retrieving the client
 MAC address of a HID device
Date: Fri, 31 Jan 2014 15:04:47 -0500
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To: Benjamin Tissoires <benjamin.tissoires@gmail.com>, Frank Praznik <frank.praznik@oh.rr.com>
Cc: linux-input <linux-input@vger.kernel.org>, Jiri Kosina <jkosina@suse.cz>, David Herrmann <dh.herrmann@gmail.com>

On 1/31/2014 14:10, Benjamin Tissoires wrote:
> Hi Frank,
>
> just a quick review:
>
> On Fri, Jan 31, 2014 at 12:32 PM, Frank Praznik <frank.praznik@oh.rr.com> wrote:
>> Currently there is no reliable way for a device module or hidraw application to
>> retrieve the client MAC address of the associated wireless device.  This series
>> of patches adds a stable way of retrieving this information.
> Well, if I look at the uevent of a Bluetooth mouse I have:
>
> $ cat /sys/devices/pci0000\:00/0000\:00\:14.0/usb3/3-2/3-2\:1.0/bluetooth/hci0/hci0\:43/0005\:046D\:B00D.001F/uevent
> DRIVER=hid-generic
> HID_ID=0005:0000046D:0000B00D
> HID_NAME=Ultrathin Touch Mouse
> HID_PHYS=00:10:60:ea:df:ae
> HID_UNIQ=00:1f:20:96:33:47
> MODALIAS=hid:b0005g0001v0000046Dp0000B00D
>
> I would say that HID_UNIQ is the client MAC address set by hidp, no?
> So you don't need to duplicate the info by adding a new field in
> hid_device.
>
In a patch I recently submitted I was using the UNIQ field for 
retrieving a Bluetooth device MAC address and was warned against it 
because "UNIQ is a way to provide unique identifiers for devices, but 
it's not guaranteed to stay the same".  HIDP happens to store the MAC in 
the UNIQ data, but there is no guarantee that it will always be there.  
With these patches you can be completely sure that the data in 
client_addr is the client device MAC address.