linux-kernel - Re: [PATCH v3 3/7] dt-bindings: ufs: common: add OPP table

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Date:   Fri, 13 May 2022 23:10:10 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Taniya Das <tdas@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-scsi@...r.kernel.org,
        Rob Herring <robh@...nel.org>
Subject: Re: [PATCH v3 3/7] dt-bindings: ufs: common: add OPP table

On Fri, May 13, 2022 at 08:13:43AM +0200, Krzysztof Kozlowski wrote:
> Except scaling UFS and bus clocks, it's necessary to scale also the
> voltages of regulators or power domain performance state levels.  Adding
> Operating Performance Points table allows to adjust power domain
> performance state, depending on the UFS clock speed.
> 
> OPPv2 deprecates previous property limited to clock scaling:
> freq-table-hz.
> 
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> Reviewed-by: Rob Herring <robh@...nel.org>
> 
> ---
> 
> Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>  .../devicetree/bindings/ufs/ufs-common.yaml   | 34 +++++++++++++++++--
>  1 file changed, 31 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/ufs/ufs-common.yaml b/Documentation/devicetree/bindings/ufs/ufs-common.yaml
> index 47a4e9e1a775..d7d2c8a136bb 100644
> --- a/Documentation/devicetree/bindings/ufs/ufs-common.yaml
> +++ b/Documentation/devicetree/bindings/ufs/ufs-common.yaml
> @@ -20,11 +20,24 @@ properties:
>        items:
>          - description: Minimum frequency for given clock in Hz
>          - description: Maximum frequency for given clock in Hz
> +    deprecated: true
>      description: |
> +      Preferred is operating-points-v2.
> +
>        Array of <min max> operating frequencies in Hz stored in the same order
> -      as the clocks property. If this property is not defined or a value in the
> -      array is "0" then it is assumed that the frequency is set by the parent
> -      clock or a fixed rate clock source.
> +      as the clocks property. If either this property or operating-points-v2 is
> +      not defined or a value in the array is "0" then it is assumed that the
> +      frequency is set by the parent clock or a fixed rate clock source.
> +
> +  operating-points-v2:
> +    description:
> +      Preferred over freq-table-hz.
> +      If present, each OPP must contain array of frequencies stored in the same
> +      order for each clock.  If clock frequency in the array is "0" then it is
> +      assumed that the frequency is set by the parent clock or a fixed rate
> +      clock source.

This description mentions only the clocks and not voltages. But in theory, the
OPP table can contain other parameters like current, bandwidth, etc,... So to
avoid confusion, I'd suggest to get rid of the description.

> +
> +  opp-table: true
>  
>    interrupts:
>      maxItems: 1
> @@ -75,8 +88,23 @@ properties:
>  
>  dependencies:
>    freq-table-hz: [ 'clocks' ]
> +  operating-points-v2: [ 'clocks', 'clock-names' ]

What about voltage regulators if relevant opp property is present?

Thanks,
Mani

>  
>  required:
>    - interrupts
>  
> +allOf:
> +  - if:
> +      required:
> +        - freq-table-hz
> +    then:
> +      properties:
> +        operating-points-v2: false
> +  - if:
> +      required:
> +        - operating-points-v2
> +    then:
> +      properties:
> +        freq-table-hz: false
> +
>  additionalProperties: true
> -- 
> 2.32.0
> 

-- 
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