linux-kernel - Re: [PATCH V2 2/3] dt-bindings: mmc: sdhci-msm: Add entries for passing load values

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Message-ID: <CAE=gft6w_iV+vm=u=ZKNvDLVTHcAO+AR0A9Yg9etTHW8bJy05w@mail.gmail.com>
Date:   Thu, 20 Sep 2018 17:15:51 -0700
From:   Evan Green <evgreen@...omium.org>
To:     vbadigan@...eaurora.org
Cc:     adrian.hunter@...el.com, Ulf Hansson <ulf.hansson@...aro.org>,
        robh+dt@...nel.org, linux-mmc@...r.kernel.org,
        asutoshd@...eaurora.org, riteshh@...eaurora.org,
        stummala@...eaurora.org, sayali <sayalil@...eaurora.org>,
        Doug Anderson <dianders@...gle.com>, vviswana@...eaurora.org,
        mark.rutland@....com, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 2/3] dt-bindings: mmc: sdhci-msm: Add entries for
 passing load values

On Wed, Sep 19, 2018 at 11:24 PM Veerabhadrarao Badiganti
<vbadigan@...eaurora.org> wrote:
>
> From: Vijay Viswanath <vviswana@...eaurora.org>
>
> The load a particular sdhc controller should request from a regulator
> is device specific and hence each device should individually vote for
> the required load.
>
> Signed-off-by: Vijay Viswanath <vviswana@...eaurora.org>
> Signed-off-by: Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
> ---
>  Documentation/devicetree/bindings/mmc/sdhci-msm.txt | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-msm.txt b/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
> index 502b3b8..3720385 100644
> --- a/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
> +++ b/Documentation/devicetree/bindings/mmc/sdhci-msm.txt
> @@ -26,6 +26,11 @@ Required properties:
>         "cal"   - reference clock for RCLK delay calibration (optional)
>         "sleep" - sleep clock for RCLK delay calibration (optional)
>
> +Optional properties:
> +- qcom,<supply>-current-level-microamp - specifies load levels for supply during BUS_ON and
> +                                       BUS_OFF states in power irq. Should be specified in
> +                                       pairs (lpm, hpm), for BUS_OFF and BUS_ON respectively.
> +                                       Units uA.
>  Example:
>
>         sdhc_1: sdhci@...24900 {
> @@ -37,6 +42,7 @@ Example:
>
>                 vmmc-supply = <&pm8941_l20>;
>                 vqmmc-supply = <&pm8941_s3>;
> +               qcom,vqmmc-current-level-microamp = <200 22000>;
>
>                 pinctrl-names = "default";
>                 pinctrl-0 = <&sdc1_clk &sdc1_cmd &sdc1_data>;
> --
> Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc., is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
>

Aren't the regulator load levels pretty coarse? Would it be safe to
say that pretty much all sd/mmc devices need the high powered mode, or
are there really some devices that can get by with LPM all the time?
-Evan