Date:   Thu, 16 Jul 2020 06:27:26 -0500
From:   Adam Ford <aford173@...il.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Stephen Boyd <sboyd@...nel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Adam Ford-BE <aford@...conembedded.com>,
        Magnus Damm <magnus.damm@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS
        <devicetree@...r.kernel.org>, Linux Kernel Mailing List" 
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arm64: dts: Introduce r8a774a1-beacon-rzg2m-kit

On Thu, Jul 16, 2020 at 2:39 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Stephen,
>
> On Thu, Jul 16, 2020 at 2:38 AM Stephen Boyd <sboyd@...nel.org> wrote:
> > Quoting Geert Uytterhoeven (2020-07-13 05:45:00)
> > > On Thu, Jul 9, 2020 at 12:00 AM Adam Ford <aford173@...il.com> wrote:
> > > > On Wed, Jul 8, 2020 at 4:53 PM Adam Ford <aford173@...il.com> wrote:
> > > > > On Mon, Jun 22, 2020 at 8:20 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > > > > > On Wed, Jun 17, 2020 at 2:05 PM Adam Ford <aford173@...il.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?
>

I owe a fix for the VC5 driver, but I was focussed on getting the new
dev kit pushed.  My goal is to have another revision of the fix pushed
today.

> > 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.

It's in the queue now, so I'll hold off.  I have a few other fires to
put out before the end of the week.

thanks,

adam
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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

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