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Using a LPSR GPIO Pad as a GPIO

Question asked by James Burnworth on Apr 3, 2018
Latest reply on Apr 4, 2018 by James Burnworth



I'm trying to configure the imx7 pad GPIO1_IO01 as a GPIO.  We have a custom base board for the iMX7D and have other, non-lpsr, GPIO working ( I can toggle them and read their values from /sys/class/gpio).  Here's a snippet from my device tree where I try to configure GPIO1_IO01 as a GPIO input with no pull and normal drive strength, no hysteresis, and fast slew. 

&iomuxc_lpsr {
      pinctrl-names = "default";
      pinctrl-0 = <&pinctrl_gpio_lpsr>;

      epilog-cs-overboard {

            pinctrl_gpio_lpsr: gpiogrp-lpsr {
                  fsl,pins = <
                        MX7D_PAD_GPIO1_IO01__GPIO1_IO1       0x00

When I read the value in /sys/class/gpio/gpio1 I always read 0 whether I pull it to ground or +3.3 V.  Do I need to do anything different for a LPSR pad in the device tree? 


Also, in other device trees I've seen lines like this for lpsr pads:

MX7D_PAD_GPIO1_IO07__I2C2_SDA 0x4000000f

What does the 0x4000000f do?  I thought the last value was only for pad control and could thus at most be 0x7f.


Thank you for the time.