linux-kernel - Re: [PATCH 5/8] arm64: dts: qcom: msm8939: Fix regulator constraints

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Message-ID: <694a8e47-b478-7ca3-006b-b0972bf7e0a6@linaro.org>
Date:   Wed, 14 Jun 2023 13:48:47 +0100
From:   Bryan O'Donoghue <bryan.odonoghue@...aro.org>
To:     Stephan Gerhold <stephan@...hold.net>,
        Bjorn Andersson <andersson@...nel.org>
Cc:     Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, Benjamin Li <benl@...areup.com>
Subject: Re: [PATCH 5/8] arm64: dts: qcom: msm8939: Fix regulator constraints

On 14/06/2023 08:16, Stephan Gerhold wrote:
> The regulator constraints for the MSM8939 devices were originally taken
> from Qualcomm's msm-3.10 vendor device tree (for lack of better
> documentation). Unfortunately it turns out that Qualcomm's voltages are
> slightly off as well and do not match the voltage constraints applied
> by the RPM firmware.
> 
> This means that we sometimes request a specific voltage but the RPM
> firmware actually applies a much lower or higher voltage. This is
> particularly critical for pm8916_l11 which is used as SD card VMMC
> regulator: The SD card can choose a voltage from the current range of
> 1.8 - 2.95V. If it chooses to run at 1.8V we pretend that this is fine
> but the RPM firmware will still silently end up configuring 2.95V.
> This can be easily reproduced with a multimeter or by checking the
> SPMI hardware registers of the regulator.
> 
> Apply the same change as for MSM8916 in commit 355750828c55 ("arm64:
> dts: qcom: msm8916: Fix regulator constraints") and make the voltages
> match the actual "specified range" in the PM8916 Device Specification
> which is enforced by the RPM firmware.
> 
> Signed-off-by: Stephan Gerhold <stephan@...hold.net>

Hrmm.

I recently found in the schematic the following table.

Supply | Default V | Range V     | Rated I | Default On
L1       1.2875      0.375-1.525   250       N
L2       1.2         0.375.1.525   600       Y
L3       1.15        0.375-1.525   350       Y
L4       2.05        1.75-3.337    250       N
L5       1.8         1.75-3.337    200       Y
L6       1.8         1.75-3.337    150       Y
L7       1.8         1.75-3.337    110       Y
L8       2.9         1.75-3.337    400       Y
L9       3.3         1.75-3.337    600       N
L10      2.8         1.75-3.337    150       N
L11      2.95        1.75-3.337    600       Y
L12      2.95        1.75-3.337    50        Y
L13      3.075       1.75-3.337    50        Y
L14      1.8         1.75-3.337    55        N
L15      1.8         1.75-3.337    55        N
L16      1.8         1.75-3.337    55        N
L17      2.85        1.75-3.337    450       N
L18      2.7         1.75-3.337    150       N

So let me see.

L8 2.9 = true
L11 2.95 = true

S3 just says 1v3 but, I take your word for it on the multi-meter 
measurement.

S4 says 2v1

This patch looks fine

Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@...aro.org>