linux-kernel - Re: [PATCH v5 02/10] dt-bindings: phy: qcom,qmp-usb: Add Glymur USB UNI PHY compatible

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Message-ID: <2a70f878-269c-1b40-2e8c-77b5851de9a1@oss.qualcomm.com>
Date: Mon, 13 Oct 2025 18:16:00 -0700
From: Wesley Cheng <wesley.cheng@....qualcomm.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, krzk+dt@...nel.org,
        conor+dt@...nel.org, konrad.dybcio@....qualcomm.com,
        dmitry.baryshkov@....qualcomm.com, kishon@...nel.org, vkoul@...nel.org,
        gregkh@...uxfoundation.org, robh@...nel.org
Cc: linux-arm-msm@...r.kernel.org, linux-phy@...ts.infradead.org,
        linux-usb@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 02/10] dt-bindings: phy: qcom,qmp-usb: Add Glymur USB
 UNI PHY compatible



On 10/13/2025 4:50 PM, Krzysztof Kozlowski wrote:
> On 14/10/2025 01:46, Wesley Cheng wrote:
>>>>>      "#clock-cells":
>>>>>        const: 0
>>>>> @@ -157,6 +160,25 @@ allOf:
>>>>>            compatible:
>>>>>              contains:
>>>>>                enum:
>>>>> +              - qcom,glymur-qmp-usb3-uni-phy
>>>>> +    then:
>>>>> +      properties:
>>>>> +        clocks:
>>>>
>>>> Missing minItems.
>>>>
>>>
>>> Hi Krzysztof,
>>>
>>> Won't the minItems be inherited by the base definition?
>>>
>>
>> Ah...are you saying to define minItems to 5 as well, since we need to
>> have all 5 clocks handles defined to work?
> 
> 
> You need the minItems constraint as well, to define the dimension
> accurately.
> 
>>
>> Thanks
>> Wesley Cheng
>>
>>>>> +          maxItems: 5
>>>>> +        clock-names:
>>>>> +          items:
>>>>> +            - const: aux
>>>>> +            - const: clkref
>>>>> +            - const: ref
>>>>
>>>> What is the difference between these two? Which block INPUTs
>>>> (important!) they represent?
>>>>
>>>
>>> clkref is the TCSR reference clock switch, and the ref is the actual CXO
>>> handle.
> 
> 
> Then this should be named somehow differently. CXO is clock. Reference
> clock is clock... To me it feels like you are describing the same clock,
> just missing some gate in TCSR. But in case these are not the same
> clocks, you need to name it accurately.
> 

Technically its all handling the same clock branch (CXO), we have the 
TCSR clkref register that allows us to gate the CXO to the USB PHY, as 
CXO is shared across several HW blocks, so it allows us to properly 
powerdown the PHY even though other clients are voting for CXO on.  Then 
we obviously have to remove our vote to the overall CXO, so that it can 
potentially be shutdown.

Maybe we can rename it to "clkref" for the CXO handle and 
"clkref_switch" for the TCSRCC handle?

Thanks
Wesley Cheng