From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Olof Johansson <olof@lixom.net>,
Linus Walleij <linus.walleij@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"arm@kernel.org" <arm@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"ksummit-discuss@lists.linuxfoundation.org"
<ksummit-discuss@lists.linuxfoundation.org>
Subject: Re: [GIT PULL] ARM: SoC fixes (and a cross-arch dt-include fix)
Date: Tue, 30 May 2017 11:13:30 +0200 [thread overview]
Message-ID: <CAMuHMdWxNFUnWJjLj7ynWJFEFMAL=TPsdVSzDtohDprC=EXnaQ@mail.gmail.com> (raw)
In-Reply-To: <CAK8P3a2E1LtCNoGkAuzwJJdQdUTB_+8d=FM2asEGkXJprvm8oQ@mail.gmail.com>
Hi Arnd,
On Tue, May 23, 2017 at 4:17 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Tue, May 23, 2017 at 11:49 AM, Geert Uytterhoeven
> <geert@linux-m68k.org> wrote:
>> On Mon, May 22, 2017 at 5:11 PM, Olof Johansson <olof@lixom.net> wrote:
>>> On Mon, May 22, 2017 at 4:44 AM, Linus Walleij <linus.walleij@linaro.org> wrote:
>>>> On Fri, May 19, 2017 at 9:34 PM, Olof Johansson <olof@lixom.net> wrote:
>>>
>>> Yeah, asking people to spread out across releases would remove
>>> dependencies a lot, but it would also slow down progress and frustrate
>>> a lot of contributors so we don't do that.
>>
>> The above works fine for new support, or for new platforms.
>>
>> There's still support being migrated from platform code to DT, which
>> requires three steps:
>> 1. New DT-aware driver support,
>> 2. DT update to use the new driver support,
>> 3. Clean up platform code after optional DTB backwards compatibility
>> grace period,
>> To make matters worse, 1 may conflict with the existing platform code,
>> and 2 must sometimes not be done before 1. Hence you may need three kernel
>> releases.
>> So we're already planning now what to clean up for v4.15 ;-)
>>
>> Would it be acceptable to do step 2 in the same release, after the driver
>> support has entered in -rc1? I know this is more than just replacing
>> numbers by symbolic values.
>
> I'd say it really depends on the individual case. Do you have a particular
> platform in mind? E.g. For some of the more obsolete platforms that
> Linus Walleij has worked on over time, we have sometimes relaxed the
> rules about clean bisection and just merged everything in parallel, knowing
> that nobody else was likely to run that code on a vanilla kernel anyway.
This is for Renesas R-Car Gen2 SoCs, so we do care about DT backward
compatibility (for a while), and about bisection.
Last headache was "[PATCH v4 00/23] soc: renesas: Add R-Car RST driver for
obtaining mode pin state" (https://lkml.org/lkml/2016/10/21/500). This used
a shared immutable branch, but that caused several merge conflicts.
Next one will be smaller, as it's not really moving functionality from
platform code to DT, but switching to a new and better clock driver framework,
so there's only the dependency of DT on the new driver
"[PATCH v2 00/10] clk: renesas: rcar-gen2: Add new CPG/MSSR drivers"
(https://lkml.org/lkml/2017/5/19/212)
I'll go create an inventory of stuff in platform code for Renesas SoCs that
still needs to be converted to DT...
Thanks!
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
next prev parent reply other threads:[~2017-05-30 9:13 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-19 19:34 [GIT PULL] ARM: SoC fixes (and a cross-arch dt-include fix) Olof Johansson
2017-05-22 11:44 ` Linus Walleij
2017-05-22 15:11 ` Olof Johansson
2017-05-23 8:27 ` [Ksummit-discuss] " Daniel Vetter
2017-05-23 9:49 ` Geert Uytterhoeven
2017-05-23 14:17 ` Arnd Bergmann
2017-05-30 9:13 ` Geert Uytterhoeven [this message]
2017-06-02 15:27 ` Arnd Bergmann
2017-05-23 16:42 ` Olof Johansson
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