[PATCH 1/2] ARM: mvebu: change order of ethernet DT nodes on Armada 38x - Russell King

From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] ARM: mvebu: change order of ethernet DT nodes on Armada 38x
Date: Fri, 29 Jan 2016 11:48:53 +0000	[thread overview]
Message-ID: <20160129114853.GQ10826@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <20160127194512.GA16638@1wt.eu>

On Wed, Jan 27, 2016 at 08:45:12PM +0100, Willy Tarreau wrote:
> On Wed, Jan 27, 2016 at 07:31:44PM +0000, Russell King - ARM Linux wrote:
> (...)
> > > For example, on the Armada 388 GP, the board has two ports, labelled
> > > GE0 and GE1. One has to know that GE0 is eth1 and GE1 is eth0, which
> > > isn't really obvious.
> > > 
> > > In order to solve this, this patch proposes to exceptionaly violate
> > > the rule of "order DT nodes by register address", and put the 0x70000
> > > node before the 0x30000 node, so that network interfaces get named in
> > > a more natural way.
> > 
> > The danger is that this will completely mess up people's existing
> > scripts/distro configuration which are now used to the current
> > labelling of the network ports.
> > 
> > Not every distro provides a sane way to deal with this...
> 
> Well, may be that's one more reason for fixing it before boards start to
> ship and run distro kernels. If some boards are already in the wild running
> on a BSP kernel, people will complain that mainline reorders their network
> ports and will stick to the BSP kernel instead.

I've checked, and we believe not many people are using mainline kernels
on clearfog.  I'll have to adjust my debian jessie setup to fix the
resulting carnage though.  On the plus side, it means that mainline
matches Marvell's kernel for interface naming.

However, I will point out that changing the DT order may fix it for now,
but if there's changes to the kernel initialisation which results in a
different probe order (eg, because of a change to the way probing works,
which is something that's been discussed a few times) it's likely that
the ethX names will change again...

In other words, what I'm saying is that there's no guarantee that
changing the DT order will always result in the desired network device
naming.

-- 
RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/
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