From mboxrd@z Thu Jan  1 00:00:00 1970
From: jason@lakedaemon.net (Jason Cooper)
Date: Mon, 3 Jun 2013 14:14:37 -0400
Subject: [PATCH] ARM: atags: add support for Marvell's u-boot
In-Reply-To: <20130603175629.GH5008@1wt.eu>
References: <1370277937-2965-1-git-send-email-thomas.petazzoni@free-electrons.com>
 <20130603171017.GN18614@n2100.arm.linux.org.uk>
 <20130603175629.GH5008@1wt.eu>
Message-ID: <20130603181437.GO3803@titan.lakedaemon.net>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Mon, Jun 03, 2013 at 07:56:29PM +0200, Willy Tarreau wrote:
> Hi Russell,
> 
> On Mon, Jun 03, 2013 at 06:10:18PM +0100, Russell King - ARM Linux wrote:
> > You know, my reaction to this is to nack it because:
> > 
> > (a) Marvell didn't talk to me about adding a new tag.
> > (b) There is an established precident that we do not pass MAC addresses
> >     to the kernel in this way (such attempts have been rejected in the
> >     past.)
> > (c) It goes completely against the design spirit of ATAGs by combining
> >     many different types and instances of information into one tag.
> > (d) It picks a tag ID without understanding how tag IDs are allocated.
> >     (the idea is 0x41NNNNVV where NNNN = machine ID for machine specific
> >     tags.)
> > 
> > Everyone who has gone around extending ATAG stuff has made exactly the
> > same mistakes time and time again - mostly stemming from the fact that
> > no one wants to talk to me up front.
> > 
> > So, this is another NACK.
> 
> I understand your points, but then what could we do to get our devices
> to have properly working ethernet interfaces ? These devices have already
> been sold, and from what I've seen they've been using this ID since at
> least the Kirkwood devices.
> 
> I found no other way to get the MAC address once the system is booted.
> I would have no problem having some board-spec code locate the atags
> and set the MAC, but it looks like the information is lost very early
> and is not available anymore soon after the boot (or at least I couldn't
> find it anywhere else).
> 
> It's really not with happiness that I had to add this part to the ATAGs,
> but because I didn't find another solution :-(

Please take a look at Sebastian's approach, it's currently a wip:

  ARM: kirkwood: proper retain MAC address workaround on DT ethernet

The discussion following that patch should give you some good ideas.

hth,

Jason.