linux-kernel - Re: [PATCH] arm64: dts: qcom: ipq9574: Fix 'l2' regulator min/max voltages

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Message-ID: <99afe9f1-f6a0-46ee-b8f3-2374dc196494@oss.qualcomm.com>
Date: Tue, 24 Jun 2025 16:38:59 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Varadarajan Narayanan <quic_varada@...cinc.com>
Cc: andersson@...nel.org, konradybcio@...nel.org, robh@...nel.org,
        krzk+dt@...nel.org, conor+dt@...nel.org, lumag@...nel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: qcom: ipq9574: Fix 'l2' regulator min/max
 voltages

On 6/24/25 8:08 AM, Varadarajan Narayanan wrote:
> On Mon, Jun 23, 2025 at 01:34:22PM +0200, Konrad Dybcio wrote:
>> On 6/23/25 1:32 PM, Varadarajan Narayanan wrote:
>>> The min and max voltages on l2 regulator is 850000uV. This was
>>> incorrectly set at 1800000uV earlier and that affected the
>>> stability of the networking subsystem.
>>>
>>> Fixes: d5506524d9d9 ("arm64: dts: qcom: ipq9574: Add LDO regulator node")
>>> Signed-off-by: Varadarajan Narayanan <quic_varada@...cinc.com>
>>> ---
>>
>> Shouldn't there be a consumer for it, instead of it being always-on?
> 
> The uniphy block is the consumer of this voltage. The PMIC configures it
> to 850000uV based on OTP settings and s/w doesn't change it as uniphy
> doesn't do scaling.

Is there a chance something in the networking part can probe before
the regulator driver, resulting in a momentary undervolting?

Konrad