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

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Message-ID: <63ad4e46-8450-4ec4-bb13-6701f5eec5f6@ixit.cz>
Date: Mon, 1 Dec 2025 22:55:40 +0100
From: David Heidelberg <david@...t.cz>
To: Casey Connolly <casey.connolly@...aro.org>,
 Konrad Dybcio <konrad.dybcio@....qualcomm.com>,
 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 13:57, 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?

Thanks
David

-- 
David Heidelberg