Hi, ----- Alexander Graf <agraf@suse.de> a écrit :
On 05.09.18 11:00, Volker Kuhlmann wrote:
On Wed 05 Sep 2018 19:42:18 NZST +1200, Alexander Graf wrote:
You need to first make sure the pin is muxed properly as GPIO and not associated with a special function:
/sys/kernel/debug/pinctrl/3f200000.gpio/pinmux-pins
Once that's clear, you can use the GPIO export to actually access the GPIO function.
Ahh, how obvious... ;-) Thanks! OK, makes sense. grep gpio4 pinmux-pins says pin 4 (gpio4): (MUX UNCLAIMED) (GPIO UNCLAIMED) and I guess it ought to not say "MUX UNCLAIMED".
But I can't find how to do that. All online instructions go straight to exporting the pin (assuming a base of 0...).
Appending [all] gpio=4=op,dh gpio=462=op,dh to /boot/efi/extraconfig.txt and rebooting makes no difference.
I'm stuck again :-(
Looks like the pin muxing actually happens automatically :)
rpi:~ # grep 'pin 4 ' /sys/kernel/debug/pinctrl/3f200000.gpio/pins pin 4 (gpio4) function gpio_in in hi; irq 83 (none) rpi:~ # echo $(( 458 + 4 )) > /sys/class/gpio/export rpi:~ # echo out > /sys/class/gpio/gpio462/direction rpi:~ # grep 'pin 4 ' /sys/kernel/debug/pinctrl/3f200000.gpio/pins pin 4 (gpio4) function gpio_out in lo; irq 83 (none) rpi:~ # echo 1 > /sys/class/gpio/gpio462/value rpi:~ # grep 'pin 4 ' /sys/kernel/debug/pinctrl/3f200000.gpio/pins pin 4 (gpio4) function gpio_out in hi; irq 83 (none)
For information, I created a wiki page for GPIO as it seems to be a problem for some people: https://en.opensuse.org/openSUSE:GPIO It is general usage information, not specific to a board (even if there are output examples) Guillaume
Alex -- To unsubscribe, e-mail: opensuse-arm+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse-arm+owner@opensuse.org
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