linux-kernel - Re: [PATCH v2 3/3] riscv: dts: sophgo: add zfh for sg2042

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Message-ID:
 <MA0P287MB226265FFA15A808221629848FE64A@MA0P287MB2262.INDP287.PROD.OUTLOOK.COM>
Date: Tue, 27 May 2025 18:22:05 +0800
From: Chen Wang <unicorn_wang@...look.com>
To: Han Gao <rabenda.cn@...il.com>
Cc: devicetree@...r.kernel.org, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Paul Walmsley <paul.walmsley@...ive.com>,
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 Alexandre Ghiti <alex@...ti.fr>, Inochi Amaoto <inochiama@...il.com>,
 linux-riscv@...ts.infradead.org, sophgo@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/3] riscv: dts: sophgo: add zfh for sg2042


On 2025/5/27 17:34, Han Gao wrote:
> On Thu, May 15, 2025 at 9:33 AM Chen Wang <unicorn_wang@...look.com> wrote:
>>
>> On 2025/5/14 23:15, Han Gao wrote:
>>> sg2042 support Zfh ISA extension [1].
>>>
>>> Link: https://occ-oss-prod.oss-cn-hangzhou.aliyuncs.com/resource//1737721869472/%E7%8E%84%E9%93%81C910%E4%B8%8EC920R1S6%E7%94%A8%E6%88%B7%E6%89%8B%E5%86%8C%28xrvm%29_20250124.pdf [1]
>>>
>>> Signed-off-by: Han Gao <rabenda.cn@...il.com>
>>> ---
>>>    arch/riscv/boot/dts/sophgo/sg2042-cpus.dtsi | 256 ++++++++++----------
>>>    1 file changed, 128 insertions(+), 128 deletions(-)
>>>
>>> diff --git a/arch/riscv/boot/dts/sophgo/sg2042-cpus.dtsi b/arch/riscv/boot/dts/sophgo/sg2042-cpus.dtsi
>>> index f483f62ab0c4..8dd1a3c60bc4 100644
>>> --- a/arch/riscv/boot/dts/sophgo/sg2042-cpus.dtsi
>>> +++ b/arch/riscv/boot/dts/sophgo/sg2042-cpus.dtsi
>>> @@ -256,11 +256,11 @@ core3 {
>>>                cpu0: cpu@0 {
>>>                        compatible = "thead,c920", "riscv";
>>>                        device_type = "cpu";
>>> -                     riscv,isa = "rv64imafdc";
>>> +                     riscv,isa = "rv64imafdc_zfh";
>> Need not touch this. "riscv,isa" is deprecated and replaced by
>> "riscv,isa-base" & "riscv,isa-extensions".
>>
>> And only adding zfh for this looks a bit werid.
>>
>> Actually, I plan to remove "riscv,isa" later, so please don't touch this
>> from now on.
> I think that since the linux kernel is the upstream for devicetree, it
> cannot yet remove riscv, isa needs to maintain compatibility.

OK, maybe it's not good to remove "riscv,isa".

Can this patch not modify "riscv,isa", but only add something for 
"riscv,isa-extensions"?

Chen


>> Thanks,
>>
>> Chen
>>
>>>                        riscv,isa-base = "rv64i";
>>>                        riscv,isa-extensions = "i", "m", "a", "f", "d", "c",
>>>                                               "ziccrse", "zicntr", "zicsr",
>>> -                                            "zifencei", "zihpm",
>>> +                                            "zifencei", "zihpm", "zfh",
>>>                                               "xtheadvector";
>>>                        thead,vlenb = <16>;
>>>                        reg = <0>;

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