linux-kernel - Re: [PATCH] soc: hisilicon: Support HCCS driver on Kunpeng SoC

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Message-ID: <e92558e2-f371-27f4-a030-04efe840cda8@huawei.com>
Date:   Mon, 15 May 2023 11:37:25 +0800
From:   "lihuisong (C)" <lihuisong@...wei.com>
To:     Sudeep Holla <sudeep.holla@....com>
CC:     Arnd Bergmann <arnd@...db.de>,
        Bjorn Andersson <andersson@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Shawn Guo <shawnguo@...nel.org>,
        <linux-kernel@...r.kernel.org>, <soc@...nel.org>,
        <wanghuiqiang@...wei.com>, <tanxiaofei@...wei.com>,
        <liuyonglong@...wei.com>, <huangdaode@...wei.com>,
        <linux-acpi@...r.kernel.org>, Len Brown <lenb@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        <devicetree@...r.kernel.org>, Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Subject: Re: [PATCH] soc: hisilicon: Support HCCS driver on Kunpeng SoC


在 2023/5/4 21:16, lihuisong (C) 写道:
>
> 在 2023/4/25 21:19, Sudeep Holla 写道:
>> On Tue, Apr 25, 2023 at 09:00:31PM +0800, lihuisong (C) wrote:
>>> For firmware, DSD way is simpler and easier to manage these virtual 
>>> platform
>>> devices, and it's an usual way in kernel.
>> Any specific examples you are referring here. We had lots of debate when
>> DSD was introduced. It must be used only when there is no standard ACPI
>> way to achieve the same. But in this I don't (yet) think that is the 
>> case.
>> Further "simplicity" is remotely not the reason why you must use DSD.
>> So until you provide me technical reasons as why _CRS can't work, I
>> have to NACK this approach. DSD in this case seems like pure hack.
>>
>>> Driver only needs to get a fixed value, like pcc-id and type, here.
>>>
>> Yes and _CRS is used to get similar such properties in ACPI. It includes
>> normally MMIO and interrupts and since GAS supports PCC and _CRS can
>> contain GAS, you must simply use that.
> Hi Sudeep,
>
> I'm tring to use CRS with GAS to report PCC channel ID and get other 
> informations driver need by address.
> I found a way to obtain the generic register information according to 
> "Referencing the PCC address space" in ACPI spec.
> And driver also get the PCC generic register information successfully.
>
> But I don't know how to set and use the address in PCC register.
> Where should this address come from?
> It seems that ACPI spec is not very detailed about this.
> Do you have any suggestions?
>
> On the other hand, we think that System Memory space + method can also 
> achieve above goal.
> What do you think of that?
>
>
Hi Sudeep,

Can you give us some suggestions about above question and idea?

Looking forward to your reply.

/Huisong