Re: [PATCH v2 2/4] dt-bindings: pinctrl: qcom,tlmm-common: document i2c pull property

[Neil Armstrong <neil.armstrong@linaro.org>]

Hi Linus,

On 26/11/2022 22:53, Linus Walleij wrote:
> On Fri, Nov 25, 2022 at 1:40 PM <neil.armstrong@linaro.org> wrote:
> 
>> As I understood, it enables an "I2C resistor" on the pin, removing the need
>> of an external pull-up resistor on the line.
>>
>> I assume the classical pull-up bias is not strong enough to replace an actual
>> resistor on the PCB.
> 
> In that case I think this should be an argument to bias-pull-up like:
> 
> bias-pull-up = <360000>;
> 
> Nominally the pull up is in ohms:
> 
>    bias-pull-up:
>      oneOf:
>        - type: boolean
>        - $ref: /schemas/types.yaml#/definitions/uint32
>      description: pull up the pin. Takes as optional argument on hardware
>        supporting it the pull strength in Ohm.
> 
> Then the driver can choose to shunt in this extra I2C resistance
> from the resistance passed as argument. So no special property
> is needed, provided you can get an idea about the resistance
> provided here.

I like this alternative, I'll try to figure out if we can find a value
to match against.

Thanks,
Neil

> 
> Yours,
> Linus Walleij