Re: [PATCH/RFC v2 0/2] arm64: dts: r8a7795: Add support for R-Car H3 ES2.0

[Sjoerd Simons <sjoerd.simons@collabora.co.uk>]

On Thu, 2017-03-30 at 13:13 +0200, Geert Uytterhoeven wrote:
> Hi Sjoerd,
> 
> On Thu, Mar 30, 2017 at 12:48 PM, Sjoerd Simons
> <sjoerd.simons@collabora.co.uk> wrote:
> > On Fri, 2017-03-24 at 14:37 +0100, Geert Uytterhoeven wrote:
> > > This patch series adds preliminary support for Renesas Salvator-X
> > > development boards equipped with revision ES2.0 of the R-Car H3
> > > Soc.
> > > 
> > >   - Patch 1 adds support for the R-Car H3 ES2.0 Soc,
> > >     While this patch is safe as-is, as it doesn't affect any
> > > existing
> > >     setups, it's probably a bit premature to apply it.
> > >   - Patch 2 adds support for Salvator-X boards with R-Car H3
> > > ES2.0.
> > >     This patch does affect existing development setups, as it
> > > changes
> > > the
> > >     name of the DTB for Salvator-X boards equipped with ES1.x
> > > SoCs.
> > >     Given most developers have access to ES1.x only, this patch
> > > must
> > > not be
> > >     applied yet.
> > 
> > Would it make more sense to add a new r8a7795-es2.dtsi and keep the
> > current dtsi for es1? Having to load different device-trees based
> > on
> > which kernel is used would be rather nasty.
> 
> We definitely considered that option.
> However, we concluded that in the end, we want to mainly support
> production
> SoCs.  Hence the default files should represent the production
> version.
> Using a preproduction SoC can be considered a special case, and thus
> needs
> a file with a special esX ID in its name.

The problem is that even though they are pre-production, these are out
there and in active use, e.g. kernelci is at least doing automated
testing on one of those in Kevins lab and should be an additional
soonish in the Collabora lab. 

And for developers it'll be extra fun if halfway through a bisect the
dts name changes..

Having a es2 in your dtb name might be a bit quirky, but it's really
just a name without other meaning :). 

> We do realize this can cause some inconveniences during the
> transition period,
> when most developers don't have access to ES2.0 SoCs yet, or have
> mixed
> environments of ES1.x and ES2.0.

Heh yeah, i'd expect we'd have a mixed environment for quite a while
given these boards are a bit too expensive to just throw in the trash..

> Of course you can keep on using the current DTB (binary) on your H3
> ES1.x
> boards, as long as you don't need to use devices not yet described in
> that DTB.
> 
> Thanks!
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linu
> x-m68k.org
> 
> In personal conversations with technical people, I call myself a
> hacker. But
> when I'm talking to journalists I just say "programmer" or something
> like that.
>                                 -- Linus Torvalds

-- 
Sjoerd Simons
Collabora Ltd.