Messages in this thread | | | Date | Fri, 25 Nov 2022 13:40:09 +0100 | From | neil.armstrong@linaro ... | Subject | Re: [PATCH v2 2/4] dt-bindings: pinctrl: qcom,tlmm-common: document i2c pull property |
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On 25/11/2022 10:47, Linus Walleij wrote: > On Thu, Nov 24, 2022 at 2:24 PM Neil Armstrong > <neil.armstrong@linaro.org> wrote: >> On 24/11/2022 14:11, Linus Walleij wrote: >>> On Wed, Nov 23, 2022 at 4:20 PM Abel Vesa <abel.vesa@linaro.org> wrote: >>> >>>> From: Neil Armstrong <neil.armstrong@linaro.org> >>>> >>>> Document the new i2c_pull property introduced for SM8550 setting >>>> an I2C specific pull mode on I2C able pins. >>>> >>>> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org> >>>> Signed-off-by: Abel Vesa <abel.vesa@linaro.org> >>> (...) >>>> + qcom,i2c-pull: >>>> + type: boolean >>>> + description: enable bias pull feature designed for I2C on pin >>> >>> But what is this? >>> >>> I2C buses are usually just plain old bias-high-impedance, high-z >>> or open drain, wire-or or whatever you want to call it. >>> >>> But now there is some special i2c mode, huh? >>> >>> The description is pretty much "it is what it is"... can we have >>> some explanation about what this means electrically speaking >>> and why you cannot use bias-high-impedance? >> >> I'll try to get some more info, but so far I only found what I wrote in the bindings. > > Björn: can you see if you can get some clarity about the i2c > bias thing?
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.
Neil
> > Yours, > Linus Walleij
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