[PATCH] Add Linux dts files and use them

[Sascha Hauer]

On Mon, May 05, 2014 at 07:57:48PM +0400, Alexander Shiyan wrote:
> Mon, 5 May 2014 10:20:49 +0200 от Sascha Hauer <s.hauer at pengutronix.de>:
> > Some updates how I intend to handle upstream dts changes in barebox.
> > 
> > - I will merge the latest upstream dts changes to barebox for each Linux
> >   rc. Should dts changes introduce regressions this will at least give us
> >   the Linux rc which introduced it
> > - I will always merge dts updates to barebox next, not to master. While
> >   dts changes may be needed in master to fix regressions on one board,
> >   they could also introduce new regressions on other boards. Should we
> >   need dts changes to fix regressions in barebox master, we have to do
> >   it using overlays in arch/*/dts/ until an upstream fix arrives in dts/
> > - I will not send the dts updates to the list, I'll just merge them to
> >   barebox next some time after a new Linux rc arrived (As just happened
> >   with 3.15-rc3)
> 
> Just to understand our further concept:
> 
> (I will use the example based on i.MX25).
> We have 3 files in the arch/arm/dts/imx25*.
> Should we now remove all of them, create our overlay for karo-tx25 board
> and include basic file <arm/imx25-karo-tx25.dts> in the top of new overlay
> file as basic DTS?

Yes, I think that's the way to go.

In the simplest case we have a arch/arm/dts/imx25-karo-tx25.dts with only a
single line:

#include <arm/imx25-karo-tx25.dts>

Then everything will be used from the upstream dts files. Additional
barebox specific stuff can be added to that file, like the environment
description.
With i.MX25 it happened that we also need SoC specific updates like for
example the iram which is not mainline. So we need a second line in
arch/arm/dts/imx25-karo-tx25.dts:

#include "imx25.dtsi"

The goal should be to mainline the SoC specific stuff so that imx25.dtsi
can be dropped, but I think we need the possibility to have SoC specific
barebox changes.

Sascha

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