Re: [PATCH v3 6/7] riscv: dts: starfive: Add initial StarFive JH7110 device tree

[Icenowy Zheng <uwu@icenowy.me>]

在 2022-12-28星期三的 22:48 +0000，Conor Dooley写道：
> Hey,
> 
> On Tue, Dec 20, 2022 at 09:12:46AM +0800, Hal Feng wrote:
> > From: Emil Renner Berthing <kernel@esmil.dk>
> > 
> > Add initial device tree for the JH7110 RISC-V SoC by StarFive
> > Technology Ltd.
> > 
> > Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> > Co-developed-by: Jianlong Huang <jianlong.huang@starfivetech.com>
> > Signed-off-by: Jianlong Huang <jianlong.huang@starfivetech.com>
> > Co-developed-by: Hal Feng <hal.feng@starfivetech.com>
> > Signed-off-by: Hal Feng <hal.feng@starfivetech.com>
> > ---
> >  arch/riscv/boot/dts/starfive/jh7110.dtsi | 411
> > +++++++++++++++++++++++
> >  1 file changed, 411 insertions(+)
> >  create mode 100644 arch/riscv/boot/dts/starfive/jh7110.dtsi
> > 
> > diff --git a/arch/riscv/boot/dts/starfive/jh7110.dtsi
> > b/arch/riscv/boot/dts/starfive/jh7110.dtsi
> > new file mode 100644
> > index 000000000000..64d260ea1f29
> > --- /dev/null
> > +++ b/arch/riscv/boot/dts/starfive/jh7110.dtsi
> > @@ -0,0 +1,411 @@
> > +// SPDX-License-Identifier: GPL-2.0 OR MIT
> > +/*
> > + * Copyright (C) 2022 StarFive Technology Co., Ltd.
> > + * Copyright (C) 2022 Emil Renner Berthing <kernel@esmil.dk>
> > + */
> > +
> > +/dts-v1/;
> > +#include <dt-bindings/clock/starfive,jh7110-crg.h>
> > +#include <dt-bindings/reset/starfive,jh7110-crg.h>
> > +
> > +/ {
> > +       compatible = "starfive,jh7110";
> > +       #address-cells = <2>;
> > +       #size-cells = <2>;
> > +
> > +       cpus {
> > +               #address-cells = <1>;
> > +               #size-cells = <0>;
> > +
> > +               S76_0: cpu@0 {
> > +                       compatible = "sifive,u74-mc", "riscv";
> 
> The label here says S76 but the compatible says u74-mc.
> Which is correct? Your docs say S7 and S76, so I would imagine that
> it
> is actually an S76?
> 
> > +                       reg = <0>;
> > +                       d-cache-block-size = <64>;
> > +                       d-cache-sets = <64>;
> > +                       d-cache-size = <8192>;
> > +                       d-tlb-sets = <1>;
> > +                       d-tlb-size = <40>;
> > +                       device_type = "cpu";
> > +                       i-cache-block-size = <64>;
> > +                       i-cache-sets = <64>;
> > +                       i-cache-size = <16384>;
> > +                       i-tlb-sets = <1>;
> > +                       i-tlb-size = <40>;
> > +                       mmu-type = "riscv,sv39";
> > +                       next-level-cache = <&ccache>;
> > +                       riscv,isa = "rv64imac";
> 
> While I was poking around trying to see if there was some logic
> behind
> that compatible, I noticed that SiFive's docs for the S76 say it is
> RV64GBC *but* the docs for the u74-mc say "4xRV64GBC and 1xRV64IMAC".
> I assume that rv64imac is the correct one here?
> 
> > +                       tlb-split;
> > +                       status = "disabled";
> > +
> > +                       cpu0_intc: interrupt-controller {
> > +                               compatible = "riscv,cpu-intc";
> > +                               interrupt-controller;
> > +                               #interrupt-cells = <1>;
> > +                       };
> > +               };
> > +
> > +               U74_1: cpu@1 {
> > +                       compatible = "sifive,u74-mc", "riscv";
> > +                       reg = <1>;
> > +                       d-cache-block-size = <64>;
> > +                       d-cache-sets = <64>;
> > +                       d-cache-size = <32768>;
> > +                       d-tlb-sets = <1>;
> > +                       d-tlb-size = <40>;
> > +                       device_type = "cpu";
> > +                       i-cache-block-size = <64>;
> > +                       i-cache-sets = <64>;
> > +                       i-cache-size = <32768>;
> > +                       i-tlb-sets = <1>;
> > +                       i-tlb-size = <40>;
> > +                       mmu-type = "riscv,sv39";
> > +                       next-level-cache = <&ccache>;
> > +                       riscv,isa = "rv64imafdc";
> 
> That also begs the question:
> Do your u74s support RV64GBC, as the (current) SiFive documentation
> suggests?

It supports RV64GCZbaZbb.

B is not a well-defined thing by specifications, so it should be
prevented here.

> 
> Thanks,
> Conor.
> 
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