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From:   Rob Herring <robh+dt@kernel.org>
Date:   Fri, 2 Nov 2018 10:11:38 -0500
Message-ID: <CAL_JsqLO+cOcHkr41ebPtONwrzOWGhksH1ypph+tihsuOVDOug@mail.gmail.com>
Subject: Re: [RFC 1/2] dt-bindings: topology: Add RISC-V cpu topology.
To:     Sudeep Holla <sudeep.holla@arm.com>
Cc:     Atish Patra <atish.patra@wdc.com>, linux-riscv@lists.infradead.org,
        Palmer Dabbelt <palmer@sifive.com>,
        Anup Patel <anup@brainfault.org>,
        Christoph Hellwig <hch@infradead.org>, Damien.LeMoal@wdc.com,
        Thomas Gleixner <tglx@linutronix.de>,
        Mark Rutland <mark.rutland@arm.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        devicetree@vger.kernel.org, alankao@andestech.com,
        Zong Li <zong@andestech.com>
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On Fri, Nov 2, 2018 at 8:31 AM Sudeep Holla <sudeep.holla@arm.com> wrote:
>
> On Fri, Nov 02, 2018 at 08:09:39AM -0500, Rob Herring wrote:
> > On Thu, Nov 1, 2018 at 6:04 PM Atish Patra <atish.patra@wdc.com> wrote:
> > >
> > > Define a RISC-V cpu topology. This is based on cpu-map in ARM world.
> > > But it doesn't need a separate thread node for defining SMT systems.
> > > Multiple cpu phandle properties can be parsed to identify the sibling
> > > hardware threads. Moreover, we do not have cluster concept in RISC-V.
> > > So package is a better word choice than cluster for RISC-V.
> >
> > There was a proposal to add package info for ARM recently. Not sure
> > what happened to that, but we don't need 2 different ways.
> >
>
> We still need that, I can brush it up and post what Lorenzo had previously
> proposed[1]. We want to keep both DT and ACPI CPU topology story aligned.

Frankly, I don't care what the ACPI story is. I care whether each cpu
arch does its own thing in DT or not. If a package prop works for
RISC-V folks and that happens to align with ACPI, then okay. Though I
tend to prefer a package represented as a node rather than a property
as I think that's more consistent.

Any comments on the thread aspect (whether it has ever been used)?
Though I think thread as a node level is more consistent with each
topology level being a node (same with package).

Rob