GPIO access as user even with rigth permissions to /sys doesn't work #36
Description
Hi
My problem is described here http://stackoverflow.com/questions/18926979/beaglebone-black-adafruit-io-python-library-gpio-user-permissions
In short: GPIO works only with root even when all permissions to /sys are OK for user and I can control gpio from user's shell, but not with python.
By experimenting I found that it works if you add delay in event_gpio.c in gpio_export function after closing file:
len = snprintf(str_gpio, sizeof(str_gpio), "%d", gpio);
write(fd, str_gpio, len);
close(fd);
volatile int i = 0; // very cruel delay
for (i = 0; i < 100000000; i++);
// add to list
new_gpio = malloc(sizeof(struct gpio_exp));
fsync(fd) and fdatasync(fd) before closing don't help. It seems like some kind of race condition which shows up only for regular user.