gpio_export: something went wrong: No such file or directory

[jshcmpbll]

Hey Guys! I am unable to use the GPIO connections on my CHIP. Any suggestions?

`root@chip:~# sudo python3 Python 3.4.2 (default, Oct 8 2014, 14:38:51) [GCC 4.9.1] on linux Type "help", "copyright", "credits" or "license" for more information.

import CHIP_IO.GPIO as GPIO GPIO.toggle_debug() debug enabled GPIO.setup("CSID0", GPIO.OUT) init_module: setup complete gpio_allowed: found match is_this_chippro: total system ram: 491.0 mb is_this_chippro: we are a chip gpio_allowed: pin allowed for chip or both and we're a chip init_r8_gpio_mem: mapping memory map_pio_memory: opening /dev/mem map_pio_memory: mapping memory map_pio_memory: moving to pio registers init_r8_gpio_mem: setup complete gpio_export gpio_export: something went wrong: No such file or directory gpio_export: creating data struct gpio_set_direction: out gpio_set_pud: port 4, pin 4, value 0 gpio_get_pud: port 4, pin 4 open_value_file **

`

[xtacocorex]

Are you properly cleaning up the GPIO before exiting out of the interpreter? What happens if you do: ls /sys/class/gpio

[miaooss]

I have the same error using python 2.7.9

root@chip:/home/chip# ls /sys/class/gpio export gpiochip0 gpiochip1013 gpiochip1021 unexport

[gerardogm]

I see the same error being displayed when debug mode is active. In my case, GPIO works even when these messages are being displayed.

I think this is caused by a small bug on function gpio_export on event_gpio.c:

    ssize_t s = write(fd, str_gpio, len);  e_no = errno;
    if (DEBUG)
        if (e_no)
            printf("gpio_export: something went wrong: %s\n", strerror(e_no));

I'm not an expert on C, but according to what I researched you should only check errno when you get an erroneous result. In this case, we should check the value returned by write first, and if it's different to the value of len, then we should check the error code the function set into errno (this check is done further in the gpio_export function and it passes in my tests). You should expect the stdlib functions to set errno only in case of error. In this case, a previous function call set the errno variable to "2" (no such file or directory), so when the code above checked errno, the error line was printed. I made a test change to print errno before and after the write call and confirmed the errno code of "2" was there before the call to write, so I think we can ignore these errors. I'll try to submit a patch for this, it's pretty simple.

[jshcmpbll]

Nice work! I haven't used the GPIO pins on my CHIP for anything and with it being so long I can't remember if this issue is the reason I never fully utilized it. Either way nice contribution!

[gerardogm]

Nice work! I haven't used the GPIO pins on my CHIP for anything and with it being so long I can't remember if this issue is the reason I never fully utilized it. Either way nice contribution!

Thanks for your kind words! And also thank you for opening this issue in the first place: it inspired me to search for an answer to this problem :)

Regards, -G.