Accessing GPIO in imx6

sameerarvikar — Thu, 11 May 2017 13:13:00 GMT

I want to change value of GPIO1_25 (phy_reset)

but following error comes

root@var-som-mx6:~# echo 25 > /sys/class/gpio/export
-sh: echo: write error: Device or resource busy

What should i do to change the value of phy reset pin

Following is current status

root@var-som-mx6:~# cat /sys/kernel/debug/gpio
GPIOs 0-31, platform/209c000.gpio, 209c000.gpio:
gpio-6 (cd ) in lo
gpio-25 (phy-reset ) out lo
gpio-28 (usb_h1_vbus ) out lo
GPIOs 32-63, platform/20a0000.gpio, 20a0000.gpio:
GPIOs 64-95, platform/20a4000.gpio, 20a4000.gpio:
GPIOs 96-127, platform/20a8000.gpio, 20a8000.gpio:
gpio-101 (tlv320aic3x reset ) out lo
gpio-111 (usb_otg_vbus ) out lo
gpio-121 (Menu ) in hi
gpio-122 (Back ) in hi
GPIOs 128-159, platform/20ac000.gpio, 20ac000.gpio:
gpio-139 (Home ) in hi
GPIOs 160-191, platform/20b0000.gpio, 20b0000.gpio:
gpio-178 (sysfs ) out lo
GPIOs 192-223, platform/20b4000.gpio, 20b4000.gpio:
gpio-200 (wlan-en-regulator ) out lo

Thanks and Regards

Re: Accessing GPIO in imx6

Carlos_Musich — Mon, 15 May 2017 20:30:31 GMT

Hi sameerarvikar,

most likely the gpio is being used by another driver, in this case no other driver can access to the gpio. You can look into the devi tree file (.dts) and look which module is using this pin. Then you can comment or delete the line where the pin is being initialized within such module and after rebuilding the dtb file you may be able to use it as a gpio.

Best regards,
TIC

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Accessing GPIO in imx6

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