linux-kernel - Re: [PATCH v2 2/3] dt-bindings: timer: Document arm, cortex-a7-timer in arch timer

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Date:   Mon, 11 Apr 2022 14:35:57 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Rob Herring <robh@...nel.org>
Cc:     Kuldeep Singh <singh.kuldeep87k@...il.com>,
        Robin Murphy <robin.murphy@....com>,
        Marc Zyngier <maz@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <marc.zyngier@....com>,
        Mark Rutland <mark.rutland@....com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 2/3] dt-bindings: timer: Document arm, cortex-a7-timer
 in arch timer

On Sun, Mar 20, 2022 at 7:56 PM Rob Herring <robh@...nel.org> wrote:
> On Fri, Mar 18, 2022 at 02:55:08AM +0530, Kuldeep Singh wrote:
> > On Thu, Mar 17, 2022 at 08:25:12PM +0000, Robin Murphy wrote:
> > > On 2022-03-17 19:15, Kuldeep Singh wrote:
> > > > Renesas RZ/N1D platform uses compatible "arm,cortex-a7-timer" in
> > > > conjugation with "arm,armv7-timer". Since, initial entry is not
> > > > documented, it start raising dtbs_check warnings.

I hadn't seen this thread, but I had already removed the unneeded
compatible value locally, and was just waiting for the merge window and
holidays to end for sending the patch...

> > > >
> > > > ['arm,cortex-a7-timer', 'arm,armv7-timer'] is too long
> > > > 'arm,cortex-a7-timer' is not one of ['arm,armv7-timer', 'arm,armv8-timer']
> > > > 'arm,cortex-a7-timer' is not one of ['arm,cortex-a15-timer']
> > > >
> > > > Document this compatible to address it. The motivation to add this
> > > > change is taken from an already existing entry "arm,cortex-a15-timer".
> > > > Please note, this will not hurt any arch timer users.
> > >
> > > Eh, if it's never been documented or supported, I say just get rid of it.
> > > The arch timer interface is by definition part of a CPU, and we can tell
> > > what the CPU is by reading its ID registers. Indeed that's how the driver
> > > handles the non-zero number of CPU-specific errata that already exist - we
> > > don't need compatibles for that.
> > >
> > > In some ways it might have been nice to have *SoC-specific* compatibles
> > > given the difficulty some integrators seem to have had in wiring up a stable
> > > count *to* the interface, but it's not like they could be magically added to
> > > already-deployed DTs after a bug is discovered, and nor could we have
> > > mandated them from day 1 just in case and subsequently maintained a binding
> > > that is just an ever-growing list of every SoC. Oh well.
> >
> > Robin, A similar discussion was already done on v1 thread. Please see
> > below for details:
> > https://lore.kernel.org/linux-devicetree/20220317065925.GA9158@9a2d8922b8f1/
> > https://lore.kernel.org/linux-devicetree/726bde76-d792-febf-d364-6eedeb748c3b@canonical.com/
> >
> > And final outcome of discussion turns out to add this compatible string.
>
> I agree with Robin on dropping. More specific here is not useful. If
> we're going to add some cores, then we should add every core
> implementation.

... So consider it gone.

https://lore.kernel.org/r/a8e0cf00a983b4c539cdb1cfad5cc6b10b423c5b.1649680220.git.geert+renesas@glider.be/

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