Re: [PATCH v3 3/3] arm64: dts: qcom: sdm845-oneplus: use generic fuel gauge compatible

[David Heidelberg <david@ixit.cz>]

On 11/09/2026 15:37, Andrew Davis wrote:
> On 9/11/26 3:21 AM, Krzysztof Kozlowski wrote:
>> On Thu, Sep 10, 2026 at 02:47:44AM +0300, Rinat Muhamedgaliev wrote:
>>> OnePlus 6 and OnePlus 6T battery packs may contain either a TI
>>> bq27411 or bq27541 fuel gauge. Use the generic ti,bq27xxx compatible
>>> so the driver can select the register map from DeviceType at probe
>>> time.
>>>
>>> Tested on OnePlus 6T (fajita) with a bq27541 (DeviceType 0x0541):
>>> after booting the new kernel, the battery reported 4.360 V, 100% state
>>> of charge, 27.8 C, and Full status.
>>>
>>> Fixes: 12dfb002ca01 ("arm64: dts: qcom: sdm845-oneplus-*: add fuel gauge")
>>
>> What is the bug here? Your commit msg should be specific about it.
>>
> 
> Commit msg seems pretty clear about the bug (to me at least), the DT
> says the fuel gauge is a BQ27411 but that isn't the case, some shipped
> with a BQ27541 fuel gauge.
> 
> (I do agree though this shouldn't have a fixes tag as back-porting this
> without also back-porting the driver-side change would break users)
> 
> Since these fuel gauges often live on the battery pack and not the
> device itself, folks changing their batteries might end up with
> different fuel gauges, so having some detection method is going to
> be helpful.
> 
> Rinat,
> 
> I'm not familiar with the bootflow on these devices, but is this something
> you could detect in the bootloader and fixup the DT before it is passed
> to kernel? That way the kernel gets a DT with the correct and specific
> compatible to start with?

Hello Andrew:

There are two possible bootflows:
a) from fastboot (we can't do anything)
b) from intermediate u-boot (we could do this)

While your suggestion seems to be the most correct, I'm not sure the 
"complexity" here outweighs the pros of simply reporting

deb_warn your phones has different charging chip

and switching the behavior to the "replacement part" here.

In the future we'll need to add u-boot logic because of camera focus, where the 
focus in some phones is on different i2c addr + from different vendor, where we 
cannot do it so simply as here.

What do you think?

David>
> Andrew
> 
>>>
>>> Signed-off-by: Rinat Muhamedgaliev <rinat.muhamedgaliev@gmail.com>
>>> ---
>>>   arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi   | 4 ++--
>>>   arch/arm64/boot/dts/qcom/sdm845-oneplus-enchilada.dts | 2 +-
>>>   arch/arm64/boot/dts/qcom/sdm845-oneplus-fajita.dts    | 2 +-
>>>   3 files changed, 4 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi b/arch/ 
>>> arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi
>>> index 948a0dd..8c5cd94 100644
>>> --- a/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi
>>> +++ b/arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi
>>> @@ -790,8 +790,8 @@ &i2c10 {
>>>       status = "okay";
>>>       clock-frequency = <100000>;
>>> -    bq27441_fg: bq27441-battery@55 {
>>> -        compatible = "ti,bq27411";
>>> +    bq27xxx_fg: fuel-gauge@55 {
>>> +        compatible = "ti,bq27xxx";
>>
>> And this is just breaking all users without any explanation.
>>
>>
>>
>>>           status = "okay";
>>>           reg = <0x55>;
>>>       };
>>> diff --git a/arch/arm64/boot/dts/qcom/sdm845-oneplus-enchilada.dts b/arch/ 
>>> arm64/boot/dts/qcom/sdm845-oneplus-enchilada.dts
>>> index 5f01115..cf40842 100644
>>> --- a/arch/arm64/boot/dts/qcom/sdm845-oneplus-enchilada.dts
>>> +++ b/arch/arm64/boot/dts/qcom/sdm845-oneplus-enchilada.dts
>>> @@ -44,7 +44,7 @@ main_cam_ois: main-cam-ois-regulator {
>>>       };
>>>   };
>>> -&bq27441_fg {
>>> +&bq27xxx_fg {
>>
>> No, irrelevant to the supposed bug here.
>>
>> Best regards,
>> Krzysztof
>>
>