From mboxrd@z Thu Jan  1 00:00:00 1970
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Subject: Re: [PATCH] arm64: dts: apq8096-db820c: Increase load on l21 for
 SDCARD
References: <1544634806-1037-1-git-send-email-loic.poulain@linaro.org>
 <8c92dc30-cfbe-00e2-ae70-243455549ecd@codeaurora.org>
 <CAMZdPi8-9d11FXKJinpJkJyhi8fcysbYVDjG8aDwbY3s=mLarw@mail.gmail.com>
From: Jeffrey Hugo <jhugo@codeaurora.org>
Message-ID: <aea60b4c-f651-5e5a-c363-f7da9a8ed838@codeaurora.org>
Date: Thu, 13 Dec 2018 07:46:37 -0700
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To: Loic Poulain <loic.poulain@linaro.org>
Cc: andy.gross@linaro.org, david.brown@linaro.org, robh+dt@kernel.org, linux-arm-msm@vger.kernel.org, bjorn.andersson@linaro.org, devicetree@vger.kernel.org
List-ID: <devicetree@vger.kernel.org>

On 12/13/2018 12:55 AM, Loic Poulain wrote:
> Hi Jeffrey,
> 
> 
> On Wed, 12 Dec 2018 at 18:23, Jeffrey Hugo <jhugo@codeaurora.org 
> <mailto:jhugo@codeaurora.org>> wrote:
> 
>     On 12/12/2018 10:13 AM, Loic Poulain wrote:
>      > In the same way as for msm8974-hammerhead, l21 load, used for SDCARD
>      > VMMC, needs to be increased in order to prevent any voltage drop
>     issues
>      > (due to limited current) happening with some SDCARDS or during
>     specific
>      > operations (e.g. write).
>      >
>      > Fixes: 660a9763c6a9 (arm64: dts: qcom: db820c: Add pm8994
>     regulator node)
>      > Signed-off-by: Loic Poulain <loic.poulain@linaro.org
>     <mailto:loic.poulain@linaro.org>>
>      > ---
>      >   arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi | 2 ++
>      >   1 file changed, 2 insertions(+)
>      >
>      > diff --git a/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi
>     b/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi
>      > index 104cad9..c15e2c0 100644
>      > --- a/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi
>      > +++ b/arch/arm64/boot/dts/qcom/apq8096-db820c.dtsi
>      > @@ -634,6 +634,8 @@
>      >                               l21 {
>      >                                       regulator-min-microvolt =
>     <2950000>;
>      >                                       regulator-max-microvolt =
>     <2950000>;
>      > +                                     regulator-allow-set-load;
>      > +                                     regulator-system-load =
>     <200000>;
>      >                               };
>      >                               l22 {
>      >                                       regulator-min-microvolt =
>     <3300000>;
>      >
> 
>     I'm curious, why not update sdhci-msm to set the load on the regulator?
> 
> 
> Yes you're right, and I saw that there is ongoing work:
> https://patchwork.kernel.org/patch/10630731/
> 
> Howerver I thought this change would be a quicker fix and easier to 
> backport in stable trees.
> I assume all the device-tree vmmc loads will be removed at some point 
> when driven from sdhci.
> 

I hadn't seen that.  Ok, seems good to me.


-- 
Jeffrey Hugo
Qualcomm Datacenter Technologies as an affiliate of Qualcomm 
Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.