linux-kernel - Re: [PATCH] arm64: dts: qcom: qcm6490: Allow UFS regulators load/mode setting

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Message-ID: <b900d558-8ab0-436f-87bd-7a3d83e3dea0@quicinc.com>
Date: Tue, 8 Oct 2024 15:08:56 +0530
From: Rakesh Kota <quic_kotarake@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: <andersson@...nel.org>, <konradybcio@...nel.org>, <robh@...nel.org>,
        <krzk+dt@...nel.org>, <conor+dt@...nel.org>,
        <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <quic_kamalw@...cinc.com>,
        <quic_jprakash@...cinc.com>
Subject: Re: [PATCH] arm64: dts: qcom: qcm6490: Allow UFS regulators load/mode
 setting



On 10/7/2024 1:37 AM, Dmitry Baryshkov wrote:
> On Fri, Oct 04, 2024 at 01:31:10PM GMT, Rakesh Kota wrote:
>> The UFS driver expects to be able to set load (and by extension, mode)
>> on its supply regulators. Add the necessary properties to make that
>> possible.
>>
>> While at it, UFS rails have different voltage requirement for UFS2.x
>> v/s UFS3.x. Bootloader sets the proper voltage based on UFS type.
>> There can be case where the voltage set by bootloader is overridden
>> by HLOS client.
>>
>> To prevent above issue, add change to remove voltage voting support
>> for dedicated UFS rails.
> 
> add change to remove smth doesn't sound correct to me.
> Please don't depend on the bootloader and describe hardware > configuration. If there can be two types of IDP boards and you can not
> identify the voltage via other means, please create something like
> qcm6490-idp-ufs3.dts. Please add proper Fixes tags.
> Last, but not least, as Bjorn wrote, please split into two patches.
> 
sure, i will split the change into two.

Since we can’t differentiate IDP boards based on UFS versions while 
loading the DT and we have only single board ID for the IDP's, it’s not 
possible to create separate UFS-based DT files like qcm6490-idp-ufs3.dts 
and ufs2.dtsi... etc.

And also UFS driver does not vote for voltage on UFS rails & they just 
vote on load only.
Hence to support both UFS 2.x and 3.x, we need to remove the voltage
min/max voting. if add the min and max voltages in DT, then those
initial voltage set by bootloader is overridden by regulator
framework with min voltage specified in DT.

Note: Bootloader have capability to detect the UFS version (where as 
HLOS does not have that capability)

Thank you for quick review!!
>>
>> Signed-off-by: Rakesh Kota <quic_kotarake@...cinc.com>
>> ---
>>   arch/arm64/boot/dts/qcom/qcm6490-idp.dts | 12 ++++++++----
>>   1 file changed, 8 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/arm64/boot/dts/qcom/qcm6490-idp.dts b/arch/arm64/boot/dts/qcom/qcm6490-idp.dts
>> index 84c45419cb8d..8a4df9c2a946 100644
>> --- a/arch/arm64/boot/dts/qcom/qcm6490-idp.dts
>> +++ b/arch/arm64/boot/dts/qcom/qcm6490-idp.dts
>> @@ -258,13 +258,15 @@ vreg_l6b_1p2: ldo6 {
>>   			regulator-name = "vreg_l6b_1p2";
>>   			regulator-min-microvolt = <1140000>;
>>   			regulator-max-microvolt = <1260000>;
>> +			regulator-allow-set-load;
>> +			regulator-allowed-modes = <RPMH_REGULATOR_MODE_LPM RPMH_REGULATOR_MODE_HPM>;
>>   			regulator-initial-mode = <RPMH_REGULATOR_MODE_HPM>;
>>   		};
>>   
>>   		vreg_l7b_2p952: ldo7 {
>>   			regulator-name = "vreg_l7b_2p952";
>> -			regulator-min-microvolt = <2400000>;
>> -			regulator-max-microvolt = <3544000>;
>> +			regulator-allow-set-load;
>> +			regulator-allowed-modes = <RPMH_REGULATOR_MODE_LPM RPMH_REGULATOR_MODE_HPM>;
>>   			regulator-initial-mode = <RPMH_REGULATOR_MODE_HPM>;
>>   		};
>>   
>> @@ -277,8 +279,8 @@ vreg_l8b_0p904: ldo8 {
>>   
>>   		vreg_l9b_1p2: ldo9 {
>>   			regulator-name = "vreg_l9b_1p2";
>> -			regulator-min-microvolt = <1200000>;
>> -			regulator-max-microvolt = <1304000>;
>> +			regulator-allow-set-load;
>> +			regulator-allowed-modes = <RPMH_REGULATOR_MODE_LPM RPMH_REGULATOR_MODE_HPM>;
>>   			regulator-initial-mode = <RPMH_REGULATOR_MODE_HPM>;
>>   		};
>>   
>> @@ -467,6 +469,8 @@ vreg_l10c_0p88: ldo10 {
>>   			regulator-name = "vreg_l10c_0p88";
>>   			regulator-min-microvolt = <720000>;
>>   			regulator-max-microvolt = <1050000>;
>> +			regulator-allow-set-load;
>> +			regulator-allowed-modes = <RPMH_REGULATOR_MODE_LPM RPMH_REGULATOR_MODE_HPM>;
>>   			regulator-initial-mode = <RPMH_REGULATOR_MODE_HPM>;
>>   		};
>>   
>> -- 
>> 2.34.1
>>
>