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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Fri, 26 Nov 2021 10:23:39 +0100
Message-ID: <CAMuHMdWAHW-RF-RrMbH=AsVmSRw=JEsUot0PaMzDdve70JfXQQ@mail.gmail.com>
Subject: Re: [PATCH] dt-bindings: timer: sifive, clint: Fix number of interrupts
To:     Anup Patel <anup@brainfault.org>
Cc:     Jessica Clarke <jrtc27@jrtc27.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Rob Herring <robh+dt@kernel.org>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Anup Patel <anup.patel@wdc.com>
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Hi Anup,

On Fri, Nov 26, 2021 at 10:15 AM Anup Patel <anup@brainfault.org> wrote:
> On Fri, Nov 26, 2021 at 2:34 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Thu, Nov 25, 2021 at 4:23 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > To improve human readability and enable automatic validation, the tuples
> > > in "interrupts-extended" properties should be grouped using angle
> > > brackets.  As the DT bindings lack an upper bound on the number of
> > > interrupts, thus assuming one, proper grouping is currently flagged as
> > > an error.
> > >
> > > Fix this by adding the missing "maxItems", limiting it to 10 interrupts
> > > (two interrupts for a system management core, and two interrupts per
> > > core for other cores), which should be sufficient for now.
> > >
> > > Group the tuples in the example.
> > >
> > > Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
> > > ---
> > >  .../devicetree/bindings/timer/sifive,clint.yaml          | 9 +++++----
> > >  1 file changed, 5 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/Documentation/devicetree/bindings/timer/sifive,clint.yaml b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > > index a35952f487426988..55bec2d059807c48 100644
> > > --- a/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > > +++ b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
> > > @@ -43,6 +43,7 @@ properties:
> > >
> > >    interrupts-extended:
> > >      minItems: 1
> > > +    maxItems: 10
> >
> > Cfr. Jessica's comment on my PLIC patch:
> >
> > The maximum supported by the CLINT memory map is 8192.
> > Device-specific limits would be 4 for k210 and jh7100, and 10 for
> > fu540.
>
> As-per CLINT chapter of SiFive FU740 manual:
> 1) Offset 0x0000 to 0x3fff is MSIPx registers (up to 4096 registers)
> 2) Offset 0x4000 to 0xbff7 is MTIMECMPx registers (up to 4095 registers)

Thanks, I had missed these are 64-bit (and did wonder about the extra
space ;-)

> 3) Offset 0xbff8 to 0xc000 is MTIME register
> (Refer, https://sifive.cdn.prismic.io/sifive/28560457-c5a4-4f88-866c-8098d02afea1_FU740-C000-Manual-v1p0.pdf)
>
> The "maxItems" for SiFive CLINT should be 4095.

OK.

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