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

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Message-ID: <fdb5e8df-017f-4891-b004-5ef919447962@oss.qualcomm.com>
Date: Tue, 2 Dec 2025 11:40:52 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: David Heidelberg <david@...t.cz>,
        Casey Connolly <casey.connolly@...aro.org>,
        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 12/1/25 10:55 PM, David Heidelberg wrote:
> On 01/12/2025 13:57, Casey Connolly wrote:
>>
>>
>> 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
>>
> 
> Thank you both, now I also understand (and withdrawing the patch).
> 
> Should
> 
> 5dcc6587fde2 ("arm64: dts: qcom: sdm845-tama: Add display nodes")
> 
> also get fixed up to not disable the lab & ibb node then?

Yes

Konrad