Hi,
While playing with sunxi SoC based board GPIOs I found out that after
exporting a GPIO it's direction is set to "in" but it's not able to
actually sense any value unless I manually write "in" to
/sys/class/gpioX/direction.
This is because on those SoCs default GPIO function is "disabled" and it
is not changed when GPIO is exported. Since "direction" only supports
two stated (in/out) there is no way this state could be represented. I
see this as a bug and would like to fix this but I'm not sure what would
be preffered way.
- write my own "request" handler instead of using
"gpiochip_generic_request" for "gpio_chip" structre (this was my first
try but sunxi dev wasn't convinced it's a good place for this change)
- keep using "gpiochip_generic_request" and write "gpio_request_enable"
handler for "pinmux_ops"
- change higher layers, like gpiolib, to enforce setting gpio direction
as input when exporting/requesting GPIO
Or maybe there is even better way of doing that? I couldn't find any
documentation that clearly states what state should GPIO be in after
requesting/exporting but clearly at least gpiolib sysfs interface expect
it to be set as input.
Best regards,
Krzysztof Adamski
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