Re: [PATCH v2 2/2] arm64: dts: qcom: sdm845-shift-axolotl: Enable NFC

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 3/25/26 9:17 PM, David Heidelberg wrote:
> On 25/03/2026 12:20, Konrad Dybcio wrote:
>> On 3/24/26 7:08 PM, David Heidelberg wrote:
>>>
>>>
>>> On 24/03/2026 14:12, Konrad Dybcio wrote:
>>>> On 3/24/26 12:20 AM, David Heidelberg via B4 Relay wrote:
>>>>> From: David Heidelberg <david@ixit.cz>
>>>>>
>>>>> Definition of the NFC.
>>>>
>>>> "meh" commit message
>>>>
>>>> [...]
>>>>
>>>>> +    nfc_enable_default: nfc-enable-default-state {
>>>>> +        pins = "gpio12", "gpio62";
>>>>> +        function = "gpio";
>>>>> +        drive-strength = <2>;
>>>>> +        bias-pull-up;
> 
>               bias-disable;
>>>>
>>>> Are you sure about pulling up an active-high pin?
>>>
>>> I'm not sure, but downstream does it (and "works for me"). Maybe Alexander would know more details here.
>>
>> Would changing it to bias-disable also "work for you"?
> 
> Yeah, works for me. Should OnePlus 6 do the same?
> 
> Looking at OP6 datasheet, there is no pull-up/down on 12,62,nor IRQ 63.

Generally the internal bias would be used to counteract random noise posing
as signal, to ensure the line is kept in the "inactive" state when not
actively driven

I can see that the driver initially requests both to LOW and then sets it to
high based on the desired mode in nxp_nci_i2c_set_mode(), so pulling up is
perhaps never really desired.

Konrad