Re: [PATCH] arm64: dts: Introduce r8a774a1-beacon-rzg2m-kit

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Stephen,

On Thu, Jul 16, 2020 at 2:38 AM Stephen Boyd <sboyd@kernel.org> wrote:
> Quoting Geert Uytterhoeven (2020-07-13 05:45:00)
> > On Thu, Jul 9, 2020 at 12:00 AM Adam Ford <aford173@gmail.com> wrote:
> > > On Wed, Jul 8, 2020 at 4:53 PM Adam Ford <aford173@gmail.com> wrote:
> > > > On Mon, Jun 22, 2020 at 8:20 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > > > On Wed, Jun 17, 2020 at 2:05 PM Adam Ford <aford173@gmail.com> wrote:
> > > > > > Beacon EmebddedWorks, formerly Logic PD is introducing a new
> > > > > > SOM and development kit based on the RZ/G2M SoC from Renesas.
> > > > > >
> > > > > > The SOM supports eMMC, WiFi and Bluetooth, along with a Cat-M1
> > > > > > cellular radio.
> > > > > >
> > > > > > The Baseboard has Ethernet, USB, HDMI, stereo audio in and out,
> > > > > > along with a vareity of push buttons and LED's.
> >
> > > > > > --- /dev/null
> > > > > > +++ b/arch/arm64/boot/dts/renesas/beacon-renesom-baseboard.dtsi
> > > > > > @@ -0,0 +1,733 @@
> > > > > > +// SPDX-License-Identifier: GPL-2.0
> > > > > > +/*
> > > > > > + * Copyright 2020, Compass Electronics Group, LLC
> > > > > > + */
> > > > > > +
> > > > > > +#include <dt-bindings/gpio/gpio.h>
> > > > > > +#include <dt-bindings/input/input.h>
> > > > > > +#include <dt-bindings/clk/versaclock.h>
> > > > >
> > > > > This depends on "[PATCH V3 2/3] dt: Add additional option bindings for
> > > > > IDT VersaClock", which hasn't been accepted yet, AFAIK.
> > >
> > > Geert,
> > >
> > > I forgot to ask.  What is the protocol for something when new bindings
> > > have been accepted in one branch, but another branch where I want to
> > > reference them hasn't merged with the other branch?  I'd really like
> > > to get this board into the next kernel.  I could remove these
> > > references and the calling functions, but that may cause instability
> > > due to undefined behaviour of some of the versaclock functions because
> > > they are not programmed.
> >
> > As soon as a binding update has been accepted into the maintainer's
> > for-next branch, I happily accept DTS patches that start using it,
> > unless doing so would introduce a regression.
> > In this case, it's not a pure binding update, but also an update to
> > binding definitions in a header file, thus creating a hard dependency.
> > Usually this is mitigated by committing the header file change to an
> > immutable branch, to be shared by driver and DTS, and to be pulled by
> > all maintainers affected by the dependency.
> >
> > As Stephen has already applied the binding update to his clk-next
> > branch, it's too late to go for the immutable branch approach.  Hence
> > the simplest solution would be to postpone your DTS patch to v5.10.
> >
> > > However, I would rather have the board mostly work if it means getting
> > > it accepted into the kernel.  Beacon hasn't shipped any outside of the
> > > company yet, so I am not really worried about people seeing problems.
> > > If the board gets accepted without these, I could apply some 'fixes'
> > > at a late date to correct the undefined behavior.  Let me know what
> > > the best way to proceed should be, and I'll send a V2 patch.
> >
> > An alternative would be for me to cherry-pick commit 34662f6e30846ae0
> > ("dt: Add additional option bindings for IDT VersaClock") from the
> > clk-next branch into renesas-devel, before applying your patch.
> > While that would help you, it may introduce a merge conflict for
> > linux-next and for upstream later, as Luca has already posted multiple
> > patches for idt,versaclock5.txt, to fix typos and do the json-schema
> > conversion.  These may or may not land in v5.9.
> >
> > Stephen: what do you think?
> > Thanks!
> >
>
> Do you need to use something in clk-next as an immutable branch?
> Typically I don't rebase patches once applying to clk-next and all
> patches are put on topic branches in case something is needed in another
> tree. So you should be fine to pull the clk-vc5 branch (which is sort of
> busted) into your dts tree, or if you need the defines/numbers in the

busted?

> header file you can use the raw numbers and then replace them with the
> includes after -rc1.

Thanks, I forgot about the raw number solution, as it's been a while I
used that.  In the meantime we solved the issue by postponing the new
VC5 options.
Adam: if you still want to send a v4 using the raw numbers, feel free
to do so.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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