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

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Date:   Fri, 21 Sep 2018 16:02:06 +0530
From:   Veerabhadrarao Badiganti <vbadigan@...eaurora.org>
To:     Evan Green <evgreen@...omium.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

Hi Evan,


On 9/21/2018 5:45 AM, Evan Green wrote:
> 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
The load levels here are min and max supported by the regulator. To 
cover all devices
we do set it to max load. We can't make any assumptions on this,  as 
peak current may vary
from device to device.

Thanks,
Veera