GPIO configurations on tx2 GPIO Expander 1 & GPIO Expander 2


for my custom carrier card, I need to configure GPIO Expanders 1 & GPIO Expanders 2 present at address 74 & 77 of i2c bus 0.

How can I configure the pins ? How can I fetch gpio pin numbers for these two devices ?


hello shrinathchoudhary,

you should access pinmux spreadsheets to check the pin naming.
please also access Jetson TX2 Platform Adaptation and Bring-Up Guide from Jetson Download Center.
you may check [GPIO Changes] session for the sample to calculate GPIO numbers.


Jetson TX2 Platform Adaptation and Bring-Up Guide talks about tranlating SOM connector pins to GPIO pins on j21

But What I want is to configure the GPIO Expanders on i2c bus 0 @74 & @77

How are they configured by default ?? if they are configured from pinmux, what are the names used in pinmux ?

hello shrinathchoudhary,

please check the sensor device tree,
for example,

you may also disassembler the dtb file into txt file for quick checking,
for example,

$ dtc -I dtb -O dts -o temp.txt $OUT/Linux_for_Tegra/kernel/dtb/tegra186-quill-p3310-1000-c03-00-base.dtb

This is a very bad solution because it did not explain what to look for in the device tree. Some of the gpio expander pins are being controlled by kernel modules and there is no information on what kernel modules to remove to free the gpio’s


grep the source code for gpio_i2c_0_74 to show the device tree entries that control the gpio expander.

Is there a entry in the .config to remove vdd-fan usage?