linux-kernel - Re: [v4 1/3] dt-bindings: phy: qcom,usb-snps-femto-v2: Add phy override params bindings

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Message-ID: <3abbb26f-9396-d024-67f6-f24f7db3408d@quicinc.com>
Date:   Fri, 13 May 2022 13:03:53 +0530
From:   Krishna Kurapati PSSNV <quic_kriskura@...cinc.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        "Andy Gross" <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Doug Anderson <dianders@...omium.org>,
        "Matthias Kaehlcke" <mka@...omium.org>,
        Wesley Cheng <quic_wcheng@...cinc.com>,
        "Vinod Koul" <vkoul@...nel.org>
CC:     <devicetree@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-phy@...ts.infradead.org>, <quic_pkondeti@...cinc.com>,
        <quic_ppratap@...cinc.com>, <quic_vpulyala@...cinc.com>,
        Sandeep Maheswaram <quic_c_sanm@...cinc.com>
Subject: Re: [v4 1/3] dt-bindings: phy: qcom,usb-snps-femto-v2: Add phy
 override params bindings


On 5/11/2022 11:49 PM, Krzysztof Kozlowski wrote:
> On 11/05/2022 17:26, Krishna Kurapati wrote:
>> From: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
>>
>> Add device tree bindings for SNPS phy tuning parameters.
>>
>> Signed-off-by: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
>> Signed-off-by: Krishna Kurapati <quic_kriskura@...cinc.com>
>> ---
>>   .../bindings/phy/qcom,usb-snps-femto-v2.yaml       | 87 ++++++++++++++++++++++
>>   1 file changed, 87 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/phy/qcom,usb-snps-femto-v2.yaml b/Documentation/devicetree/bindings/phy/qcom,usb-snps-femto-v2.yaml
>> index 1ce251d..70efffe 100644
>> --- a/Documentation/devicetree/bindings/phy/qcom,usb-snps-femto-v2.yaml
>> +++ b/Documentation/devicetree/bindings/phy/qcom,usb-snps-femto-v2.yaml
>> @@ -53,6 +53,93 @@ properties:
>>     vdda33-supply:
>>       description: phandle to the regulator 3.3V supply node.
>>   
>> +  qcom,hs-disconnect-bps:
>> +    $ref: /schemas/types.yaml#/definitions/int32
>> +    description:
>> +      This adjusts the voltage level for the threshold used to
>> +      detect a disconnect event at the host. Possible values are.
>> +      The values defined are in multiples of basis points (1bp = 0.01%).
> This means there is some minimum and maximum (100%)?
>
>> +      The hardware accepts only discrete values. The value closest to the
>> +      provided input will be chosen as the override value for this param.
>> +
>> +  qcom,squelch-detector-bps:
>> +    $ref: /schemas/types.yaml#/definitions/int32
>> +    description:
>> +      This adjusts the voltage level for the threshold used to
>> +      detect valid high-speed data.
>> +      The values defined are in multiples of basis points (1bp = 0.01%).
>> +      The hardware accepts only discrete values. The value closest to the
>> +      provided input will be chosen as the override value for this param.
>> +
>> +  qcom,hs-amplitude-bps:
>> +    $ref: /schemas/types.yaml#/definitions/int32
>> +    description:
>> +      This adjusts the high-speed DC level voltage.
>> +      The values defined are in multiples of basis points (1bp = 0.01%).
>> +      The hardware accepts only discrete values. The value closest to the
>> +      provided input will be chosen as the override value for this param.
>> +
>> +  qcom,pre-emphasis-duration-bps:
>> +    $ref: /schemas/types.yaml#/definitions/int32
>> +    description:
>> +      This signal controls the duration for which the
>> +      HS pre-emphasis current is sourced onto DP<#> or DM<#>.
>> +      The HS Transmitter pre-emphasis duration is defined in terms of
>> +      unit amounts. One unit of pre-emphasis duration is approximately
>> +      650 ps and is defined as 1X pre-emphasis duration.
>> +      The values defined are in multiples of basis points (1bp = 0.01%).
>> +      The hardware accepts only discrete values. The value closest to the
>> +      provided input will be chosen as the override value for this param.
>> +
>> +  qcom,pre-emphasis-amplitude-bps:
>> +    $ref: /schemas/types.yaml#/definitions/int32
>> +    description:
>> +      This signal controls the amount of current sourced to
>> +      DP<#> and DM<#> after a J-to-K or K-to-J transition.
>> +      The HS Transmitter pre-emphasis current is defined in terms of unit
>> +      amounts. One unit amount is approximately 2 mA and is defined as
>> +      1X pre-emphasis current.
>> +      The values defined are in multiples of basis points (1bp = 0.01%).
>> +      The hardware accepts only discrete values. The value closest to the
>> +      provided input will be chosen as the override value for this param.
>> +
>> +  qcom,hs-rise-fall-time-bps:
>> +    $ref: /schemas/types.yaml#/definitions/int32
>> +    description:
>> +      This adjusts the rise/fall times of the high-speed waveform.
>> +      The values defined are in multiples of basis points (1bp = 0.01%).
>> +      The hardware accepts only discrete values. The value closest to the
>> +      provided input will be chosen as the override value for this param.
>> +
>> +  qcom,hs-crossover-voltage-mv:
>> +    $ref: /schemas/types.yaml#/definitions/int32
>> +    description:
>> +      This adjusts the voltage at which the DP<#> and DM<#>
>> +      signals cross while transmitting in HS mode.
>> +      The values defined are in milli volts. The hardware accepts only
>> +      discrete values. The value closest to the provided input will be
>> +      chosen as the override value for this param.
>> +
>> +  qcom,hs-output-impedance-mohm:
>> +    $ref: /schemas/types.yaml#/definitions/int32
> Here and in other places, please use standard units. See
> dtschema/schemas/property-units.yaml in dtschema repo.
>
>
> Best regards,
> Krzysztof

Hi Krzystof, thanks for the input.

I see there are microvolt and microohm units present in 
schemas/property-units.yaml

Would it be possible to add bps (basis point) to the list of standard 
units if it makes sense to use it ?

Regards,

Krishna,