Subject: [PATCH 04/12] ARM: shmobile: r8a7740: Add DT name to clock list for CMT10

From: [email-masked] (Arnd Bergmann)
Date: Fri, 31 May 2013 23:39:05 +0200

On Friday 31 May 2013, Magnus Damm wrote:
> With mach-shmobile we have deliberately chosen to avoid AUXDATA. The
> reason for that is that we keep the DT version of a device clean from
> the beginning so it is kept totally free of platform data while in
> parallel we also have a regular platform device with platform data for
> the old legacy C version of board support. Other ARM subarchitectures
> seem to use DT together with platform data which is a step that we
> prefer to skip by using a C version and a DT version of board support
> in parallel. The idea is that we should be able to existing level of
> support in the C version while incrementally doing development on the
> DT -reference code. Then drop the C version when the DT version has
> become good enough. Current blockers are GPIO/PFC DT and common clock
> framework.

I think this makes sense and you we shouldn't force you as the platform
maintainer to do it the other way. Incrementally removing the auxdata
and platform_data structures as most platforms do is nice in the sense
that it allows you to have a fully working system booting with DT
from the start and to reduce the amount of code as early as possible,
and for instance this has worked rather well on kirkwood/orion/dove/mvebu.

The price for that method is that you end up having to coordinate patches
carefully between subsystems so you first add DT support to a driver,
and then atomically change the dts file and the board file to the
method. With your way, you can avoid a lot of the trouble we've seen
on other platforms with complex dependency graphs or broken
bisection.

> > Where are you guys at on your plans for getting DT_based clock going? That will
> > sort of indicate just how temporary these clock alaises will be. I'm guessing
> > we'll be living with them for a while though?
> 
> I have to deal with LPAE soon according to my todo list. After that I
> will make sure common clock conversion starts moving. There are many
> SoCs to convert, so it will have to happen gradually. I doubt we will
> get any code ready for merge in v3.11, getting some bits into v3.12 is
> probably possible.
> 
> Apart from moving to common clocks and after that adding support for a
> single multi-subarch kernel binary, is there anything you want us to
> implement? Anything for v3.11? I'd like to get the memory bits sorted
> out if possible.

My preference would be if you can get CONFIG_MULTIPLATFORM to work on
as many of your SoCs as possible, but that depends on having at least
some support for COMMON_CLK.

	Arnd