Re: [PATCH 3/5] arm: initial support for Marvell Dove SoCs

From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
To: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Cc: barebox@lists.infradead.org,
	Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Subject: Re: [PATCH 3/5] arm: initial support for Marvell Dove SoCs
Date: Mon, 13 May 2013 16:23:13 +0200	[thread overview]
Message-ID: <20130513162313.4f5849a9@skate> (raw)
In-Reply-To: <5190E56F.9080903@gmail.com>

Dear Sebastian Hesselbarth,

On Mon, 13 May 2013 15:06:55 +0200, Sebastian Hesselbarth wrote:

> > Please note that normally barebox images are expected to be runnable
> > second stage (bootm barebox.bin). Though not really mandatory this still
> > is a nice feature for development. This becomes difficult to support if
> > the initial code expects the registers at 0xd0000000, hence I suggested
> > remapping it in the kwb image so that all second stage code can already
> > work on the remapped registers.
> 
> Yeah, this is bugging Thomas and me for some time. The tricky part in
> this is, that the register for setting the internal register base is in
> the internal registers itself. You don't know the base address, you
> cannot remap it - you can't even read it. Thomas is working on
> something, but he will have to comment on that.

One solution for Barebox is to have a DATA line in our kwbimage.cfg
that does:

DATA 0xd0020080 0xf1000000

and so when Barebox boots, the remapping to 0xf1 is already done, and
we don't have to worry about it. This way, a Barebox can chainload a
second Barebox.

> I will flip through the patches we have for DT and see if we have a
> stable MVEBU like what is in -next now first or rework it before it
> moves to stable. I want Thomas to fully comment on my DT patches first,
> but I guess he is busy ATM.
> 
> Regarding DT, I sent a patch that adds basic address translation we need
> because we are heavily using "ranges" property in our dtbs. We should
> also add pci and isa bus style mapping, but that can come later.
> 
> There is more issues I found with boolean properties but haven't
> investigated yet.

I believe we should get your existing Dove patches merged, merge the
Kirkwood patches I have almost ready, and only then converge on the DT +
remapping support. Would you agree with this plan?

Thanks,

Thomas
-- 
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com

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