Changing configuration of pin #189 or pin #191 (I2C1_SCL/SDA) in spreadsheet has no effect in dtsi file

In the Xavier pinmux spreadsheet, changing the “Required Initial State” of pin #189 (I2C1_SCL) or pin #191 (I2C1_SDA) to “Int PU” has no effect on the tegra19x-jetson_xavier_nx_module-pinmux.dtsi file generated by the spreadsheet. In fact, there appears to be no mention of the ball names of the two pins (“dp_aux_ch3_p” and “dp_aux_ch3_n”) in the file at all.

What is the default configuration of these pins? Are they configurable, and if so, how?

Many thanks

Hi tony.aldhous,

Please refer to the following default configuration for these 2 pins.

It seems blank for “Required Initial State” since they are configured as I2C.

You could just configure the column of “Customer Usage” for the desired function.
Do you want to use them as I2C or GPIO?

The problem I am investigating is to do with a level changer connected to the I2C lines. I noticed that changing whether the pin had pull-up resistors or not changed the device tree for pins #185/#187 and pins #232/#234, but not for pints #189/#191.

I tried changing the “customer usage” #189 from I2C9_CLK to DP_AUX_CH3_P, to see if it had any effect. The generated dtsi file was unchanged. (Note, the board name was “jetson_xavier_nx_module”). It seems that changes to the configuration pins #189 and #191 are ignored.

The data sheet (DS-10184-001-v1.9) states that there is an “2.2kΩ pull-up to 3.3V on module” on pins #185 (I2C0_SDL), #187 (I2C0_SDA), #189 (I2C1_SCL), #191(I2C1_SDA), #232 (I2C2_SCL), #234 (I2C2_SDA). Does this mean that changing the whether the pin has a pull-up or not has no effect?


Please check the column of Ext Pull Up Value (Ω), it seems all of them have 2.2K pull-up resistors.

How do you configure for this?

This can be done by clearing the value in the “Ext Pull Up Value” column and setting the value “Required Initial State” column to “Int PU”.

The question I have is why changing values for the two pins #189 (I2C1_SCL) or pin #191 (I2C1_SDA) has no effect in the generated DTSI, whereas changing the values for the pins #185/#187 and pins #232/#234 does have an effect. I am concerned that properties for the two pins #189 and #191 may be missing from the generated device tree.

It seems the issue is coming from I2C9 (#189 and #191) not listed in generated pinmux.dtsi.
I’m checking this with internal.

I’ve checked this issue with internal that Xavier NX pin 189 and 191 (I2C1) configuratyion is not included in the dtsi file because these IO pads are not controlled by the GPIO controller. I2C1 is pinmuxed with DPAUX function and the IO configuration is set by the ARDPAUX registers thru the display driver SW.

Thanks for response. Can you confirm that the pins default to the i2c functions, and are switched to the display port function if required by the display driver.

Yes, it is default configured as i2c.
You could check dpaux@155F0000 node in your device tree.

Perfect! Thank you.

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