linux-kernel - Re: [PATCH V2 1/3] dt-bindings: interconnect: Add EPSS L3 compatible for SA8775P

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Message-ID: <00c9feac-722a-481a-9c57-36463fe0b3ff@quicinc.com>
Date: Mon, 4 Nov 2024 12:10:27 +0530
From: Raviteja Laggyshetty <quic_rlaggysh@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: Georgi Djakov <djakov@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio
	<konradybcio@...nel.org>,
        Sibi Sankar <quic_sibis@...cinc.com>, <linux-arm-msm@...r.kernel.org>,
        <linux-pm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Odelu Kukatla
	<quic_okukatla@...cinc.com>,
        Mike Tipton <quic_mdtipton@...cinc.com>
Subject: Re: [PATCH V2 1/3] dt-bindings: interconnect: Add EPSS L3 compatible
 for SA8775P



On 11/1/2024 12:26 AM, Dmitry Baryshkov wrote:
> On Wed, Oct 30, 2024 at 12:23:57PM +0530, Raviteja Laggyshetty wrote:
>>
>>
>> On 10/26/2024 8:15 PM, Dmitry Baryshkov wrote:
>>> On Sat, Oct 26, 2024 at 12:30:56PM +0000, Raviteja Laggyshetty wrote:
>>>> Add Epoch Subsystem (EPSS) L3 interconnect provider binding on
>>>> SA8775P SoCs.
>>>>
>>>> Signed-off-by: Raviteja Laggyshetty <quic_rlaggysh@...cinc.com>
>>>> ---
>>>>  .../devicetree/bindings/interconnect/qcom,osm-l3.yaml         | 4 ++++
>>>>  1 file changed, 4 insertions(+)
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/interconnect/qcom,osm-l3.yaml b/Documentation/devicetree/bindings/interconnect/qcom,osm-l3.yaml
>>>> index 21dae0b92819..042ca44c32ec 100644
>>>> --- a/Documentation/devicetree/bindings/interconnect/qcom,osm-l3.yaml
>>>> +++ b/Documentation/devicetree/bindings/interconnect/qcom,osm-l3.yaml
>>>> @@ -34,6 +34,10 @@ properties:
>>>>                - qcom,sm8250-epss-l3
>>>>                - qcom,sm8350-epss-l3
>>>>            - const: qcom,epss-l3
>>>> +      - items:
>>>> +          - enum:
>>>> +              - qcom,sa8775p-epss-l3
>>>> +          - const: qcom,epss-l3-perf
>>>
>>> Why is it -perf? What's so different about it?
>>
>> The EPSS instance in SA8775P uses PERF_STATE register instead of REG_L3_VOTE to scale L3 clocks.
>> So adding new generic compatible "qcom,epss-l3-perf" for PERF_STATE register based l3 scaling.
> 
> Neither sm8250 nor sc7280 use this compatible, while they also use
> PERF_STATE register.
> 
That is correct, both sm8250 and sc7280 use perf state register.
The intention for adding "qcom,epss-l3-perf" generic compatible is to use it for the chipsets which use perf state register for l3 scaling.
Using generic compatible avoids the need for adding chipset specific compatible in match table.
>>
>>
>>>
>>>>  
>>>>    reg:
>>>>      maxItems: 1
>>>> -- 
>>>> 2.39.2
>>>>
>>>
>>
>