linux-kernel - Re: [PATCH 3/8] arm64: dts: qcom: msm8916: Fix regulator constraints

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Message-ID: <cf03b068-2d2d-45e4-f724-83304992550e@nexus-software.ie>
Date:   Fri, 26 May 2023 16:42:50 +0100
From:   Bryan O'Donoghue <pure.logic@...us-software.ie>
To:     Stephan Gerhold <stephan@...hold.net>,
        Bjorn Andersson <andersson@...nel.org>
Cc:     Andy Gross <agross@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, phone-devel@...r.kernel.org,
        ~postmarketos/upstreaming@...ts.sr.ht
Subject: Re: [PATCH 3/8] arm64: dts: qcom: msm8916: Fix regulator constraints

On 17/05/2023 19:48, Stephan Gerhold wrote:
> The regulator constraints for most MSM8916 devices (except DB410c) 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.
> 
> Fix this by making 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>

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