Tegra gpio driver: Need to configure pins in gpio mode/nontristate with gpio-request

Laxman Dewangan ldewangan at nvidia.com
Thu May 5 06:16:45 EDT 2011


Hi All,
When working on gpio driver for tegra, I found that gpio_request() does not
make the corresponding soc pins to gpio mode. It still keeps the pins in SFIO mode.
So we need to call two extra function along with gpio_request():
Tegra_gpio_enable() and function for setting the pins in no non-tristate.

Sue to this, the gpio sysfs interface does not work properly from user space /sys/class/gpio/.
To make the pin in gpio mode fom user space, need to have changes in kernel.

I think the gpio_request() should make the pins to gpio mode and make ready for use.
Similarly gpio_free() should again put the pin into sfio mode with tristate disable.

Please comment if there is any better way..


Thanks,
Laxman



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