Subject: Re: [alsa-devel] [PATCH 1/2] powerpc: add platform registration for ALSA SoC drivers

From: Benjamin Herrenschmidt <[email-masked]>
Date: Thu, 29 Apr 2010 10:42:56 +1000

On Wed, 2010-04-28 at 14:00 +0100, Mark Brown wrote:
> > The whole thing is a matter of common sense and a bit of taste :-)
> 
> The impression that has been created in the past is that there are
> inflexible device tree rules which can't be varied.

I'm a bit sad this is how things have been perceived since that's
clearly not the policy I've applied to the powerpc architecture.

Or rather, there are -some- inflexible rules yes, which are to:

 - Have a device-tree :-)

 - Have a /compatible property at the toplevel to identify your board

 - Have the /cpus nodes for representing the CPUs.

That's pretty much the only absolute requirements from a code
perspective.

Now I -do- require people to also have nodes for things like PCI host
bridge, since that allows using a ton of existing code for handling most
aspects of PCI, and I -do- complain if people just hard wire platform
devices everywhere or interrupt numbers without even trying to consider
using the device-tree appropriately.

However, I've always been against the one-bsp-fits-all approach, and
it's always been my clear policy that there should be a per-machine .c
file. I did bend when folks pushed the "simple" platform but with the
understanding that it must contain an -explicit- list of boards it
supports.

You'll also notice that all of my virtual interrupt handling stuff is
such that you -can- use it without device-tree nodes, the DT just makes
it easier. Same goes with PCI devices (only the PHB requires a DT node
at this stage) etc... 

Cheers,
Ben.