linux-kernel - Re: [PATCH V4 01/14] dt-bindings: cpufreq: mediatek: Add MediaTek CCI property

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Message-ID: <811bf944-a230-ab9b-583a-840e57af8a1e@linaro.org>
Date:   Fri, 22 Apr 2022 19:34:53 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Rex-BC Chen <rex-bc.chen@...iatek.com>, rafael@...nel.org,
        viresh.kumar@...aro.org, robh+dt@...nel.org, krzk+dt@...nel.org,
        matthias.bgg@...il.com
Cc:     jia-wei.chang@...iatek.com, roger.lu@...iatek.com,
        hsinyi@...gle.com, khilman@...libre.com,
        angelogioacchino.delregno@...labora.com, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH V4 01/14] dt-bindings: cpufreq: mediatek: Add MediaTek CCI
 property

On 22/04/2022 19:26, Krzysztof Kozlowski wrote:
> On 22/04/2022 09:52, Rex-BC Chen wrote:
>> MediaTek Cache Coherent Interconnect (CCI) uses software devfreq module
>> for scaling clock frequency and adjust voltage.
>> The phandle could be linked between CPU and MediaTek CCI for some
>> MediaTek SoCs, like MT8183 and MT8186.
>> Therefore, we add this property in cpufreq-mediatek.txt.
>>
>> Signed-off-by: Rex-BC Chen <rex-bc.chen@...iatek.com>
>> ---
>>  .../devicetree/bindings/cpufreq/cpufreq-mediatek.txt         | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek.txt b/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek.txt
>> index b8233ec91d3d..3387e1e2a2df 100644
>> --- a/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek.txt
>> +++ b/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek.txt
>> @@ -20,6 +20,11 @@ Optional properties:
>>  	       Vsram to fit SoC specific needs. When absent, the voltage scaling
>>  	       flow is handled by hardware, hence no software "voltage tracking" is
>>  	       needed.
>> +- mediatek,cci:
>> +	MediaTek Cache Coherent Interconnect (CCI) uses the software devfreq module to
>> +	scale the clock frequency and adjust the voltage.
> 
> Devfreq is a SW mechanism, it should not be part of bindings description.
> 
>> +	For details, please refer to
>> +	Documentation/devicetree/bindings/interconnect/mediatek,cci.yaml
> 
> Since the file does not exist, I have troubles reviewing it. First of
> all, you already have "mediatek,cci-control" property in DT, so why
> using different name?
> 
> Second, it looks like you want to put devfreq into bindings instead of
> using proper interconnect bindings.

Actually judging by the driver this looks like some
device-boot-time-ordering, so I wonder whether this is a proper way to
express it.


Best regards,
Krzysztof