Re: [RFC v2 6/6] riscv: dts: thead: convert isa detection to new properties

[Icenowy Zheng <uwu@icenowy.me>]

在 2023-09-25星期一的 16:59 +0100，Conor Dooley写道：
> On Sun, Sep 24, 2023 at 07:22:30AM +0800, Icenowy Zheng wrote:
> > 在 2023-09-22星期五的 09:13 +0100，Conor Dooley写道：
> > > From: Conor Dooley <conor.dooley@microchip.com>
> > > 
> > > Convert the th1520 devicetrees to use the new properties
> > > "riscv,isa-base" & "riscv,isa-extensions".
> > > For compatibility with other projects, "riscv,isa" remains.
> > > 
> > > Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
> > > ---
> > >  arch/riscv/boot/dts/thead/th1520.dtsi | 12 ++++++++++++
> > >  1 file changed, 12 insertions(+)
> > > 
> > > diff --git a/arch/riscv/boot/dts/thead/th1520.dtsi
> > > b/arch/riscv/boot/dts/thead/th1520.dtsi
> > > index ce708183b6f6..723f65487246 100644
> > > --- a/arch/riscv/boot/dts/thead/th1520.dtsi
> > > +++ b/arch/riscv/boot/dts/thead/th1520.dtsi
> > > @@ -20,6 +20,9 @@ c910_0: cpu@0 {
> > >                         compatible = "thead,c910", "riscv";
> > >                         device_type = "cpu";
> > >                         riscv,isa = "rv64imafdc";
> > > +                       riscv,isa-base = "rv64i";
> > > +                       riscv,isa-extensions = "i", "m", "a",
> > > "f",
> > > "d", "c", "zicntr", "zicsr",
> > > +                                              "zifencei",
> > > "zihpm";
> > 
> > Zfh is supported by T-Head C9xx with float too.
> 
> You say xx, so just to be sure: Is it always supported, or only with
> some config for the IP (I wanna know if I need to look out for it
> while
> reviewing other SoCs etc)?

I think it's grouped with FD.

> Also, do you have a link to the documentation for it? English is the
> only relevant language I speak, so if the doc is in Chinese, I'll
> need
> some help!

Sorry, but T-Head's official document [1] is only in Chinese. In
addition, in this document half-float is listed as a "T-Head
extension", but the encoding matches Zfh. See 15.6 Appendix B-6 Half
Float (15.6 附录 B-6 浮点半精度指令术语) .

[1]
https://github.com/T-head-Semi/openc910/blob/main/doc/%E7%8E%84%E9%93%81C910%E7%94%A8%E6%88%B7%E6%89%8B%E5%86%8C.pdf

> 
> > In addition, should X extensions get listed here?
> 
> Yes, but someone who cares about documenting these extensions should
> do
> it ;)

Well at least a bunch of Xthead's are now documented.

Maybe they will get appended after this patchset get introduced.

By the way, how to deal with the draft V of C9xx?

> 
> Thanks,
> Conor.