Re: [PATCH 1/2] Documentation: bindings: Add DT bindings for ARM's FVP models.

["Jon Medhurst (Tixy)" <tixy@linaro.org>]

On Tue, 2016-06-21 at 16:33 -0500, Rob Herring wrote:
> On Tue, Jun 21, 2016 at 02:38:32PM +0100, Jon Medhurst (Tixy) wrote:
> > On Tue, 2016-06-21 at 08:22 -0500, Rob Herring wrote:
> > > > +Required properties (in root node):
> > > > +- compatible value:
> > > > +     compatible = "arm,<family>,<variant>", "arm,<family>";
> > > > +  where <family> is one of:
> > > > +  - "fvp-base" for the Base FVP
> > > > +  - "fvp-ve" for the VE FVP
> > > > +  and <variant> is the part of the model's executable filename with
> > > the family
> > > > +  name omitted, converted to lower case, and with non-alphanumeric
> > > characters
> > > > +  replaced with '-'. E.g. the Base FVP that has two AEMv8 CPU
> > > clusters has an
> > > > +  executable file called FVP_Base_AEMv8A-AEMv8A, so the compatible
> > > value for
> > > 
> > > Naming conventions of the exe aren't going to change?
> > 
> > Almost certainly will at some point, as will the very name Fixed Virtual
> > Platform, what 'families' ARM produce and their naming, and the
> > configuration of the 'hardware' compiled into the models.
> > 
> > These are software models, so can be changed easily at the whim of
> > marketing, or current perceived requirements from engineers and
> > managers. So generally, it's a moving target, that doesn't fit nicely
> > into the needs producing device-trees.
> 
> Then do we even need to specify something so specific? The kernel 
> probably doesn't even care.

Well, it would certainly be easier if we could just use a simple
'arm,fvp' for compatible and model name and not worry about the 100 or
so current variants. (Some are 32-bit, some 64-bit with just about every
current ARM CPU represented, plus various peripheral sets with regard to
display, iommu, dma, etc.


>  Are you going to upstream new strings 
> everytime there's a new one (that's public)?

I've only been asked to upstream a device-tree for the one that ARM
targets in its 'platform release' [1]. Note, all 100+ models are equally
'public' in the sense that they are available to people are pay (like
real hardware supported by Linux).

[1] https://community.arm.com/docs/DOC-10803)

> 
> We've had models supported upstream for a long time. What's changed now?

ARM's software releases are targeting a different model.

-- 
Tixy