linux-kernel - Re: [PATCH] arm64: dts: qcom: sdm845-oneplus: labibb is not used on OnePlus 6/6T

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Message-ID: <92c1609c-735d-4b5b-85ff-c40995aab813@linaro.org>
Date: Mon, 1 Dec 2025 13:57:28 +0100
From: Casey Connolly <casey.connolly@...aro.org>
To: Konrad Dybcio <konrad.dybcio@....qualcomm.com>, david@...t.cz,
 Bjorn Andersson <andersson@...nel.org>,
 Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, phone-devel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: qcom: sdm845-oneplus: labibb is not used on
 OnePlus 6/6T



On 01/12/2025 13:55, Konrad Dybcio wrote:
> On 12/1/25 1:50 PM, Casey Connolly wrote:
>>
>>
>> On 01/12/2025 13:48, Konrad Dybcio wrote:
>>> On 11/30/25 1:08 AM, David Heidelberg via B4 Relay wrote:
>>>> From: David Heidelberg <david@...t.cz>
>>>>
>>>> The lab and ibb regulators aren't used here. Disable them.
>>>>
>>>> Removes following warnings:
>>>> qcom-lab-ibb-regulator c440000.spmi:pmic@3:labibb: Failed to create device link (0x180) with supplier c440000.spmi for /soc@...pmi@...0000/pmic@...abibb/lab
>>>> qcom-lab-ibb-regulator c440000.spmi:pmic@3:labibb: Failed to create device link (0x180) with supplier c440000.spmi for /soc@...pmi@...0000/pmic@...abibb/ibb
>>>
>>> These are only vaguely related, as there's nothing to be wary about that's
>>> specific to these devices - it's just devlink being grumpy
>>>
>>>> Fixes: 288ef8a42612 ("arm64: dts: sdm845: add oneplus6/6t devices")
>>>> Signed-off-by: David Heidelberg <david@...t.cz>
>>>> ---
>>>> I assume this is right approach, as OLEDs on both devices are driven by
>>>> different regulators.
>>>>
>>>> Question is, if should be labibb nodes enabled by default?
>>>
>>> They're onboard. I'd rather keep them predictably parked than left in
>>> whatever (potentially ON) state the bootloader may leave them at
>>
>> Shouldn't they be default disabled in the pmic dtsi and only enabled on
>> the devices that actually use them? Many SDM845 devices with OLED panels
>> don't use these regulators.
> 
> As I said, I wouldn't be surprised if they were enabled by the bootloader
> as part of some reference/common routine and left hanging. Linux will
> switch them off if they're never used and I'm fairly sure the users won't
> mind the odd couple dozen bytes of runtime kernel memory usage (which if
> we go that route probably balance out with the added couple characters for
> status=disabled in the resulting DTB)

Ahh yeah I understand, the DT node has to be enabled for the driver to
load and actually turn off the regulators if they're unused. Makes sense.

Thanks,>
> Konrad

-- 
// Casey (she/her)