linux-kernel - Re: [PATCH v8 08/24] dt-bindings: clock: Add RPMI clock service message proxy bindings

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Message-ID: <175359739515.3513.8664828076215459722@lazor>
Date: Sat, 26 Jul 2025 23:23:15 -0700
From: Stephen Boyd <sboyd@...nel.org>
To: Anup Patel <apatel@...tanamicro.com>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Bartosz Golaszewski <brgl@...ev.pl>, Conor Dooley <conor+dt@...nel.org>, Jassi Brar <jassisinghbrar@...il.com>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Linus Walleij <linus.walleij@...aro.org>, Michael Turquette <mturquette@...libre.com>, Mika Westerberg <mika.westerberg@...ux.intel.com>, Rafael J . Wysocki <rafael@...nel.org>, Rob Herring <robh@...nel.org>, Thomas Gleixner <tglx@...utronix.de>, Uwe Kleine-König <ukleinek@...nel.org>, Palmer Dabbelt <palmer@...belt.com>, Paul Walmsley <paul.walmsley@...ive.com>, Alexandre Ghiti <alex@...ti.fr>, Len Brown <lenb@...nel.org>, Sunil V L <sunilvl@...tanamicro.com>, Rahul Pathak <rpathak@...tanamicro.com>, Leyfoon Tan <leyfoon.tan@...rfivetech.com>, Atish Patra <atish.patra@...ux.dev>, Andrew Jones <ajones@...tanamicro.com>, Samuel Holland <samuel.holland@...ive.com>, Anup Patel <anup@...infault.org>, linux-clk@...r.kernel.org, devicetree@...r.kernel.org, linux-acp
 i@...r.kernel.org, linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, Conor Dooley <conor.dooley@...rochip.com>
Subject: Re: [PATCH v8 08/24] dt-bindings: clock: Add RPMI clock service message proxy bindings

Quoting Anup Patel (2025-07-25 09:16:12)
> On Fri, Jul 25, 2025 at 8:12 AM Stephen Boyd <sboyd@...nel.org> wrote:
> >
> > Quoting Anup Patel (2025-07-04 00:03:40)
> > > Add device tree bindings for the RPMI clock service group based
> > > message proxy implemented by the SBI implementation (machine mode
> > > firmware or hypervisor).
> > >
> > > The RPMI clock service group is defined by the RISC-V platform
> > > management interface (RPMI) specification.
> > >
> > > Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>
> > > Signed-off-by: Anup Patel <apatel@...tanamicro.com>
> > [...]
> > > +additionalProperties: false
> > > +
> > > +examples:
> > > +  - |
> > > +    clock-controller {
> >
> > Maybe the name should be 'clock-service' then? I don't understand SBI so
> > not sure why this is in DT to begin with. Is something consuming this
> > node? Or a driver is binding to it?
> 
> SBI is a syscall style interface between SBI implementation (aka
> M-mode firmware or hypervisor) and supervisor software (aka
> Linux kernel).
> 
> We have DT based drivers in OpenSBI (M-mode firmware). This
> binding allows Clock message proxy driver to be probed on the
> OpenSBI side. The clock message proxy driver allows Linux
> RPMI clock driver to send RPMI messages via OpenSBI as
> proxy thereby sharing the RPMI transport between OpenSBI
> and Linux kernel.

Let me try to clarify my confusion. A 'clock-controller' node without a
'#clock-cells' property is confusing.

It's not providing clks? The SBI firmware is not discoverable? Do you
have a pointer to the DTS for this node and the clock controller node in
the next patch? I'd like to understand why this is named a clock
controller when it doesn't provide clks.