From mboxrd@z Thu Jan  1 00:00:00 1970
From: jason@lakedaemon.net (Jason Cooper)
Date: Mon, 3 Jun 2013 14:41:48 -0400
Subject: [PATCH] ARM: atags: add support for Marvell's u-boot
In-Reply-To: <20130603183057.GA9868@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>
 <20130603181437.GO3803@titan.lakedaemon.net>
 <20130603183057.GA9868@1wt.eu>
Message-ID: <20130603184148.GQ3803@titan.lakedaemon.net>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On Mon, Jun 03, 2013 at 08:30:57PM +0200, Willy Tarreau wrote:
> 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.

ahhh, that's annoying.  :-(

> 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 :-(

I assume they are in the u-boot environment.  As such, the only answer
may be to have user space utilities like flash-kernel parse the
environment and then customize the appended DT for the specific board.

Once the Marvell u-boot is upgraded to support fdt, they will hopefully
support editing the DT before it is passed.  All they have to do is
leave bootm alone :-/

thx,

Jason.