From mboxrd@z Thu Jan  1 00:00:00 1970
From: w@1wt.eu (Willy Tarreau)
Date: Mon, 3 Jun 2013 20:30:57 +0200
Subject: [PATCH] ARM: atags: add support for Marvell's u-boot
In-Reply-To: <20130603181437.GO3803@titan.lakedaemon.net>
References: <1370277937-2965-1-git-send-email-thomas.petazzoni@free-electrons.com>
 <20130603171017.GN18614@n2100.arm.linux.org.uk>
 <20130603175629.GH5008@1wt.eu> <20130603181437.GO3803@titan.lakedaemon.net>
Message-ID: <20130603183057.GA9868@1wt.eu>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

Hi Jason,

On Mon, Jun 03, 2013 at 02:14:37PM -0400, Jason Cooper wrote:
> > 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.

I remember this discussion, but it is different and does not apply here.
Sebastian fixed an issue with a properly configured NIC which used to
lose its MAC, so the solution consisted in saving it early in the DT.

In the mv_neta case, the NICs are not configured yet and we need to
find the MAC somewhere. I only found it in the ATAGs and nowhere else.
Well, in fact u-boot sets it on the MAC used to boot from the network
if such a boot is performed, but that's all. So in practice you boot
without the MAC address anywhere but in the ATAGs. I'd be happy to
find a way to parse non-standard atags in a board-specific file but
they're lost early it seems :-(

Thanks,
Willy