linux-kernel - Re: [PATCH v2 06/11] dt-bindings: timer: Add Sophgo sg2042 clint

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Message-ID: <IA1PR20MB49538AD51ADC3349B2AE8542BBFFA@IA1PR20MB4953.namprd20.prod.outlook.com>
Date:   Fri, 22 Sep 2023 16:18:27 +0800
From:   Inochi Amaoto <inochiama@...look.com>
To:     Conor Dooley <conor@...nel.org>
Cc:     Anup Patel <apatel@...tanamicro.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        aou@...s.berkeley.edu, chao.wei@...hgo.com,
        evicetree@...r.kernel.org, emil.renner.berthing@...onical.com,
        guoren@...nel.org, jszhang@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org, palmer@...belt.com,
        paul.walmsley@...ive.com, robh+dt@...nel.org,
        xiaoguang.xing@...hgo.com, Chen Wang <wangchen20@...as.ac.cn>,
        Inochi Amaoto <inochiama@...look.com>
Subject: Re: [PATCH v2 06/11] dt-bindings: timer: Add Sophgo sg2042 clint

>
>On Fri, Sep 22, 2023 at 01:16:35PM +0800, Inochi Amaoto wrote:
>
>>>> The SiFive CLINT has flexibility related limitations which makes it
>>>> not useful for multi-socket and mult-die systems. The SiFive CLINT
>>>> is also not useful for systems with AIA because with AIA M-mode has
>>>> a new way of doing M-mode IPIs. Due to this reasons, the RISC-V
>>>> ACLINT spec breaks down traditional SiFive CLINT into two separate
>>>> devices namely mtimer and mswi. This allows platforms to implement
>>>> only the required set of devices. The mtimer as defined by the ACLINT
>>>> specifications also allows platforms to place mtime and mtimecmp
>>>> registers at different locations.
>>>>
>>>> Refer, https://github.com/riscv/riscv-aclint/blob/main/riscv-aclint.adoc
>>>>
>>>> We need a separate DT bindings document for ACLINT MTIMER
>>>> and ACLINT MSWI because these are separate devices. The
>>>> Sophgo sg2042 SoC should add their implementation specific
>>>> compatible strings in this document.
>>>
>>> If the spec isn't frozen, I'm not accepting a binding for the "generic"
>>> version of it. Bindings for this specific implemtnation are okay.
>>> For sure though, squeezing this into the sifive,plic binding isn't
>>> appropriate.
>>>
>>
>> It seems I have missed a point. I wonder whether it is better to add a
>> "aclint" binding firstly and then add sg2042 to it, or just use sg2042
>> specific binding?
>
>sg2042 specific, being frozen is a requirement for merging patches
>related to RVI specifications.
>

Thanks

>> If use "aclint" binding, I wonder it is OK to add
>> thead quirks as compatible specific properties, or left this to the SBI to
>> handle? e.g. T-HEAD timer is not 64bit timer, and we should identify this.
>
>The compatible string alone should be sufficient to identify the width
>of the timer etc.
>

OK, I will take it

>Thanks,
>Conor.
>