linux-kernel - Re: [PATCH v1 1/2] scsi: dt-bindings: ufs: Add vcc-voltage-level for UFS

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Message-ID: <20200915044154.GB670377@yoga>
Date:   Mon, 14 Sep 2020 23:41:54 -0500
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     "Bao D. Nguyen" <nguyenb@...eaurora.org>
Cc:     cang@...eaurora.org, asutoshd@...eaurora.org,
        martin.petersen@...cle.com, linux-scsi@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        Avri Altman <Avri.Altman@....com>,
        Vinod Koul <vkoul@...nel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 1/2] scsi: dt-bindings: ufs: Add vcc-voltage-level for
 UFS

On Tue 01 Sep 01:00 CDT 2020, Bao D. Nguyen wrote:

> UFS's specifications supports a range of Vcc operating
> voltage levels. Add documentation for the UFS's Vcc voltage
> levels setting.
> 
> Signed-off-by: Can Guo <cang@...eaurora.org>
> Signed-off-by: Asutosh Das <asutoshd@...eaurora.org>
> Signed-off-by: Bao D. Nguyen <nguyenb@...eaurora.org>
> ---
>  Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
> index 415ccdd..7257b32 100644
> --- a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
> +++ b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
> @@ -23,6 +23,8 @@ Optional properties:
>                            with "phys" attribute, provides phandle to UFS PHY node
>  - vdd-hba-supply        : phandle to UFS host controller supply regulator node
>  - vcc-supply            : phandle to VCC supply regulator node
> +- vcc-voltage-level     : specifies voltage levels for VCC supply.
> +                          Should be specified in pairs (min, max), units uV.

What exactly are these pairs representing?

Is this supposed to be 3 pairs of (min,max) for vcc, vcc and vccq2 to be
passed into a regulator_set_voltage() for each regulator?

Or are these some sort of "operating points" for the vcc-supply?

Regards,
Bjorn

>  - vccq-supply           : phandle to VCCQ supply regulator node
>  - vccq2-supply          : phandle to VCCQ2 supply regulator node
>  - vcc-supply-1p8        : For embedded UFS devices, valid VCC range is 1.7-1.95V
> -- 
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> a Linux Foundation Collaborative Project
>