Problem exporting and accessing GPIO42


#1

Hello, I have problem with GPIO42, I am trying to export GPIO42 such way:
echo 42 > /sys/class/gpio/export
but Legato responds sh: write error: Device or resource busy
I have already configured GPIO42 using AT command AT+WIOCFG=42,16,1,1,0,0,0 but i still receive this error, how can I unlock GPIO42?


GPIO access via Legato application
#2

It looks like GPIO42 is held by the system, is there any way to release it and use it in my app?


#3

This is a known issue that has been fixed in the Linux kernel. I have quoted the relevant section of the Legato Linux source code release notes.

mdm9615: Defer claiming of IRQ GPIO for TI wifi chip refs/changes/40/9440/3

TI’s WL18XX device is not part of any MDM9615 platform; it was
intended that a daughter card with device is added to the MangOH
platform. If the IRQ GPIO for this device is allocated at boot
time, then any other device in slot 0 of MangOH platform wouldn’t
be able to claim it.

Defer allocation of this GPIO until a daughter card in slot 0 is
detected. GPIO will be claimed by a separate MangOH module that
performs this detection.

Resolves:LXSWI9X1517-51

The source code is available here: http://source.sierrawireless.com/resources/legato/legatolinuxdist/

If you are looking for an easier solution than rebuilding the kernel, then you will have to wait until release 13 of the WP firmware is available here: http-//source.sierrawireless.com/resources/legato/wpfirmwarerelease/ It seems like that could be available in a couple of weeks. Note: I had to intentionally break my previous link because “new users are only allowed to post 2 links in a post”. Just replace the “-” with “:”


#4

thank you for clearing this up.