linux-kernel - Re: [PATCH v2 1/3] dt-bindings: riscv: sifive: Add SiFive Private L2 cache controller

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Message-ID: <CAPqJEFrObCSEXx+qTOp_JY3m5Ano59x=U4fFCBJ32ufLUx+6PA@mail.gmail.com>
Date:   Fri, 28 Jul 2023 16:24:08 +0800
From:   Eric Lin <eric.lin@...ive.com>
To:     Conor Dooley <conor.dooley@...rochip.com>
Cc:     Conor Dooley <conor@...nel.org>, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        devicetree@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, zong.li@...ive.com,
        greentime.hu@...ive.com, vincent.chen@...ive.com
Subject: Re: [PATCH v2 1/3] dt-bindings: riscv: sifive: Add SiFive Private L2
 cache controller

Hi Conor,

On Fri, Jul 28, 2023 at 3:06 PM Conor Dooley <conor.dooley@...rochip.com> wrote:
>
> On Thu, Jul 20, 2023 at 06:10:51PM +0100, Conor Dooley wrote:
> > Hey Eric,
> >
> > On Thu, Jul 20, 2023 at 09:51:19PM +0800, Eric Lin wrote:
> > > This add YAML DT binding documentation for SiFive Private L2
> > > cache controller
> > >
> > > Signed-off-by: Eric Lin <eric.lin@...ive.com>
> > > Reviewed-by: Zong Li <zong.li@...ive.com>
> > > Reviewed-by: Nick Hu <nick.hu@...ive.com>
> > > ---
> > >  .../bindings/cache/sifive,pl2cache.yaml       | 62 +++++++++++++++++++
> >
> > btw, your $subject should be "dt-bindings: cache: ...." rather than
> > "riscv: sifive".
> >

OK, I'll fix it in v3.

> > >  1 file changed, 62 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/cache/sifive,pl2cache.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/cache/sifive,pl2cache.yaml b/Documentation/devicetree/bindings/cache/sifive,pl2cache.yaml
> > > new file mode 100644
> > > index 000000000000..ee8356c5eeee
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/cache/sifive,pl2cache.yaml
> > > @@ -0,0 +1,62 @@
> > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > > +# Copyright (C) 2023 SiFive, Inc.
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/cache/sifive,pl2cache.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: SiFive Private L2 Cache Controller
> > > +
> > > +maintainers:
> > > +  - Greentime Hu  <greentime.hu@...ive.com>
> > > +  - Eric Lin  <eric.lin@...ive.com>
> >
> > There's extra spaces in these lines for some reason.
> >

OK, I'll fix it in v3.

> > > +
> > > +description:
> > > +  The SiFive Private L2 Cache Controller is per core and
> > > +  communicates with both the upstream L1 caches and
> > > +  downstream L3 cache or memory, enabling a high-performance
> > > +  cache subsystem.
> > > +
> > > +allOf:
> > > +  - $ref: /schemas/cache-controller.yaml#
> > > +
> >
> > I'm pretty sure that I pointed out last time around that you need to add
> > something like in the ccache driver:
> >
> > select:
> >   properties:
> >     compatible:
> >       contains:
> >         enum:
> >           - sifive,ccache0
> >           - sifive,fu540-c000-ccache
> >           - sifive,fu740-c000-ccache
> >
> > otherwise this binding will be used for anything containing "cache" in
> > the dt-binding.
> > For this binding, I think that the following is sufficient:
> >
> > select:
> >   properties:
> >     compatible:
> >       contains:
> >           const: sifive,pl2cache1
> >

Sorry, I misunderstood your meaning.
To be honest, I'm not quite familiar with the usage of the select property.
When should we use the select property?
May I ask, is there a document to detail introduce each property and
its usage like the device-tree spec?
I think it would be very helpful for beginners writing correct
dt-binding and it can save much reviewers time.
Thanks for your kind explanation, I'll fix it in v3.

> > > +properties:
> > > +  compatible:
> > > +    items:
> > > +      - const: sifive,pl2cache1
> > > +      - const: cache
> >
> > You omitted the pl2cache0 from here, that needs to come back! You'll end
> > up with 2 items entries.

OK, it should be as follows, right?

+properties:
+  compatible:
+    oneOf:
+      - items:
+          - const: sifive,pl2cache0
+          - const: sifive,pl2cache1
+          - const: cache
+      - items:
+          - const: sifive,pl2cache1
+          - const: cache

I'll fix it in v3. Thanks.

> > Either way, I can't take this binding without a soc-specific compatible,
> > per sifive-blocks-ip-versioning.txt..
>
> Further, "sifive,perfmon-counters" is an undocumented property.
>

OK, I'll add "sifive,perfmon-counters" property in v3.
Thanks for your kind review.

Best regards,
Eric Lin

> Thanks,
> Conor.