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Subject: Re: "local-[bd|mac]-address" inconsistency?
From:   Marcel Holtmann <marcel@holtmann.org>
In-Reply-To: <20191118201551.GJ27773@google.com>
Date:   Tue, 19 Nov 2019 06:19:28 +0100
Cc:     Andre Heider <a.heider@gmail.com>, linux-bluetooth@vger.kernel.org
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Message-Id: <5F04BF9F-B975-41BE-854B-1B11691A0321@holtmann.org>
References: <57775d51-7de2-a32c-8b23-aba611483f51@gmail.com>
 <20191118201551.GJ27773@google.com>
To:     Matthias Kaehlcke <mka@chromium.org>
Sender: linux-bluetooth-owner@vger.kernel.org
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Hi Matthias,

>> when passing both addresses through device-tree in the same way:
>> $ hexdump /proc/device-tree/soc/ethernet@5020000/local-mac-address
>> 0000000 0702 3d96 53d4
>> 
>> $ hexdump /proc/device-tree/soc/serial@5000400/bluetooth/local-bd-address
>> 0000000 0703 3d96 53d4
>> 
>> I get this for eth (which is consistent with u-boot):
>> link/ether 02:07:96:3d:d4:53
>> 
>> But for bt it's in reverse order:
>> Controller 53:D4:3D:96:07:03
>> 
>> Is this intended?
> 
> Kind of.
> 
> In both cases the address is specified in the binary format used by BT/NW
> stack.
> 
> When BT addresses are printed they are converted from LSB to MSB.
> 
>> Do I really have to pass the bdaddr from u-boot in another way?
> 
> One could make a case that we don't care what the 'internal' format is and
> that the BD_ADDR should be specified in MSB format in the DT, and the kernel
> would be in charge of converting it to LSB. However I fear it is too late to
> consider a change at this point, since the binding has been in the kernel for
> 6 months with the current format and existing devices may rely on it.

we used a different property name for reason. Even while BD_ADDR is allocated from an OUI space, it has nothing in common with a MAC address.

Regards

Marcel