BeagleBone Black and GPIO issues

["Dr. Nicola Mingotti" <nmingotti%gmail.com@localhost>]

Hi,

I detected this unexpected behavior in the GPIO of the BeagleBone Black 
in NetBSD10.X

The report is divided in the RELEASE and CURRENT sessions

The experiment are run in parallel on 2 separate BBB boards.

=======================================================
====== RELEASE 10.0 ===================================
=======================================================

-------------------- ON BOARD LED ---------------------
This example is taken from here: 
https://wiki.netbsd.org/ports/evbarm/beaglebone/
---- gpio.conf ----
gpio1 21 set out USR0
gpio1 22 set out USR1
gpio1 23 set out USR2
-------------------

$> reboot
$> doas gpioctl gpio1 USR0 0    # no effect
$> doas gpioctl gpio1 USR0 1    # no effect
$> doas gpioctl gpio1 USR0 2    # no effect
--------------------------------------------------------

----- input pin --------------
---- gpio.conf -----
gpio1 17 set in       # according to my map this is pin P9_23
--------------------

$> reboot
$> # it gets accepted but it does not work
# . gpio1.17 connected to nothing
$> doas gpioctl gpio1 17
0  # => ok
# . pin 9_23 connected to P9_3 (3.3v)
$> doas gpioctl gpio1 17
0  # => BAD, it should be one


----- input pin in pull-down ------------
---- gpio.conf -----
gpio1 17 set in pd
---------------------

$> reboot
$> doas gpioctl gpio1 17
..
there is no "17"
..
$> doas gpioctl gpio1 17
gpioctl: GPIOREAD: Operation not permitted


=======================================================
=======================================================


====================================
====== CURRENT =====================
====================================

(*) ON BOARD LED, case seen before, WORKS

(*) GPIO INPUT PIN, case seen before, WORKS

(*) GPIO INPUT PIN in PULL DOWN, NOT WORKING
---- gpio.conf --------
gpio1 17 set pd
-----------------------
$> reboot
... in the serial console i see
Configuring GPIO.
gpioctl: GPIOSET: Operation not supported by device
$>  gpioctl gpio1 17
gpioctl: GPIOREAD: Operation not permitted

---- gpio.conf -------
gpio1 17 set in pd
----------------------
Configuring GPIO.
gpioctl: GPIOSET: Operation not supported by device
... as before


(*) LOOP-BACK   => WORKING

. one input pin reads another output pin
. Since here things are working quite well I do also a loop-back test
# . connect with a wire P9_27 and P9_23
---- gpio.conf -----
gpio1 17 set in   # P9_23
gpio3 21 set out  # P9_25
gpio3 21 0
--------------------
pulce5# gpioctl gpio1 17
pin 17: state 0
pulce5# gpioctl gpio3 21 1
pin 21: state 0 -> 1
pulce5# gpioctl gpio1 17
pin 17: state 1
# => OK, it is working


====================================
====================================


In conclusion, if one of my board is not broken the RELEASE
is not in good condition.

Let's focus on CURRENT which is almost OK !
what it misses is the ability to set the pin in pull-down,
which is very important.

It is quite late, i hope i did not make to many mistakes ;)

bye
Nicola