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

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Hi Linus,

On 26/11/2022 22:53, Linus Walleij wrote:
On Fri, Nov 25, 2022 at 1:40 PM <neil.armstrong@xxxxxxxxxx> 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




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