Gpio_apalis_tk1_k20 GPIOs always high

Technical Support
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1

Hi there,

I can load the driver for the K20 GPIO expansion:

modprobe gpio-apalis-tk1-k20

And dmesg confirms:

Firmware version 0.9.
gpiochip_add: registered GPIOs 856 to 1015 on device: generic

So let’s go on:

echo 952 > /sys/class/gpio/export
cat /sys/kernel/debug/gpio
[...]
GPIOs 856-1015, platform/apalis-tk1-k20-gpio, can sleep:
 gpio-952 (sysfs               ) in  hi
GPIOs 1016-1023, platform/as3722-pinctrl, as3722-gpio, can sleep:
 gpio-1018 (+V3.3               ) out hi

Looks good in principle, but it says “hi”, even if the Pin is indeed pulled low (yes, confirmed twice it’s that very pin, also tried with others). I can even do

echo low > /sys/class/gpio/gpio952/direction
cat /sys/kernel/debug/gpio
[...]
GPIOs 856-1015, platform/apalis-tk1-k20-gpio, can sleep:
 gpio-952 (sysfs               ) out hi

This is true for several GPIO ports I checked.
How to debug what’s going wrong here?

(I’m using a 3.10.40 kernel with some custom modifications. Devicetree untouched for spidev1.)
Only odd observation: When erasing K20 firmware and flashing it new, I get

apalis-tk1-k20 spi1.1: K20 FIFO Bug!
gpio wake34 for gpio=82
apalis-tk1-k20 spi1.1: Apalis TK1 K20 MFD driver.

But as I’m able to load the gpio driver afterwards, I suppose this FIFO bug is not critical.

2

Can you update BSP to version 2.7 and try again? You can disregard the “K20 FIFO Bug!”.

3

THank you for your answer. Yes, indeed it works with apalis-tk1 3.10.40-2.7.2. Strange, because out BSP is based on that, I think. How do I find out what’s wrong with our BSP? The gpio-apalis-tk1-k20 driver?

4

Good, that it is working. Can you check for the differences in the gpio-apalis-tk1-k20 between your bsp and the bsp 2.7.2?