[WP8548] GPIO42: Failed to export

IoT Modules WP Series
1

Hello Forum,

The export of gpio 42 fails since WP85 Firmware Packages - Release 10.1.

I tried to reproduce the problem with different WP85 Firmware Packages below:
Release 11 : Export failed
Release 10.1: Export failed
Release 9 : Export OK
My custom firmware based on Legato Linux Source Distribution : Same, export failed.

Logs:
Release 11:

Linux swi-mdm9x15 3.14.29ltsi-5d7a6bf7c6_ed88cc68b5 #2 PREEMPT Sat Feb 6 02:37:18 PST 2016 armv7l GNU/Linux
root@swi-mdm9x15:~# legato version
16.04.0_63633d9200de787b7c2a6dca03d2cff3
root@swi-mdm9x15:/sys/class/gpio# echo 42 >export 
sh: write error: Device or resource busy

Release 10.1:

Linux swi-mdm9x15 3.14.29ltsi-13c67b16ff_922830eb31 #2 PREEMPT Fri Apr 15 02:38:16 PDT 2016 armv7l GNU/Linux
root@swi-mdm9x15:~# legato version
16.01.2_9e91388c2b14980a4d419259910a4d65
root@swi-mdm9x15:~# echo 42 >/sys/class/gpio/export 
sh: write error: Device or resource busy

Release 9:

root@swi-mdm9x15:~# uname -a
Linux swi-mdm9x15 3.14.29ltsi-5d7a6bf7c6_ed88cc68b5 #2 PREEMPT Sat Feb 6 02:37:18 PST 2016 armv7l GNU/Linux
root@swi-mdm9x15:~# legato version
16.01.0.Beta_aa0684bddf31f5ea2d457b53d2218972
root@swi-mdm9x15:~# echo 42 >/sys/class/gpio/export 
root@swi-mdm9x15:~# ls -l /sys/class/gpio/
export
gpio42 -> ../../devices/virtual/gpio/gpio42
gpiochip1 -> ../../devices/virtual/gpio/gpiochip1
gpiochip100 -> ../../devices/i2c-0/0-003a/swimcu-gpio/gpio/gpiochip100
gpiochip88 -> ../../devices/platform/msm_ssbi.0/pm8018-core/pm8xxx-gpio/gpio/gpiochip88
gpiochip94 -> ../../devices/platform/msm_ssbi.0/pm8018-core/pm8xxx-mpp/gpio/gpiochip94
unexport

Custom:

Linux swi-mdm9x15 3.14.29ltsi-c14b887744_39dcf2256d #9 PREEMPT Mon Aug 8 14:31:12 CEST 2016 armv7l GNU/Linux
root@swi-mdm9x15:~# legato version
16.04.0_3445c2362e943b77dec2698ac3a47630
root@swi-mdm9x15:~# echo 42 >/sys/class/gpio/export 
sh: write error: Device or resource busy

Best regards,
Sylvain

2

This is a known issue related to support being added for TI wl18xx WiFi IoT module in Release 10.1. The WiFi module driver configures GPIO42 and prevents it from being used for other purposes, even if the WiFi module is not present.