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cdsteinkuehler / beaglebone-universal-io

Device tree overlay and support scripts for using most available hardware I/O on the BeagleBone without editing dts files or rebuilding the kernel
GNU General Public License v2.0
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Multiple overlays #29

Closed bobvanderlinden closed 9 years ago

bobvanderlinden commented 9 years ago

I'm not sure I'm understanding the readme, but I guessed if I wanted to use all pins, I'd do the following:

config-pin overlay cape-universal
config-pin overlay cape-univ-emmc
config-pin overlay cape-univ-hdmi

This works fine for me, but once I try to configure the pins I get this error for a number of them:

WARNING: GPIO pin not exported, cannot set direction or value!

It seems the GPIO sysfs files (/sys/class/gpio/gpio*/direction) aren't there for the last two overlays (emmc, hdmi), but they are for the first loaded overlay. This also goes when I switch the order in which I load the overlays. It seems only the first one loads correctly, all overlays after that cannot be used correctly.

If I check the slots file it seems the overlays are loaded correctly. You can also see that I've disabled the default capes in uEnv.txt:

$ cat /sys/devices/bone_capemgr.9/slots
 0: 54:PF--- 
 1: 55:PF--- 
 2: 56:PF--- 
 3: 57:PF--- 
 4: ff:P-O-- Bone-LT-eMMC-2G,00A0,Texas Instrument,BB-BONE-EMMC-2G
 5: ff:P-O-- Bone-Black-HDMI,00A0,Texas Instrument,BB-BONELT-HDMI
 6: ff:P-O-- Bone-Black-HDMIN,00A0,Texas Instrument,BB-BONELT-HDMIN
 7: ff:P-O-L Override Board Name,00A0,Override Manuf,cape-univ-emmc
 8: ff:P-O-L Override Board Name,00A0,Override Manuf,cape-univ-hdmi
 9: ff:P-O-L Override Board Name,00A0,Override Manuf,cape-universal

I've used the following config-pin file to test what was happening: https://gist.github.com/bobvanderlinden/7fa5012acf00eac1bd0e

I've tried all this with the latest machinekit image on a BeagleBone Black.

Is this the correct way to use config-pin? Could you give some more information that would let me use any pin as gpio?

cdsteinkuehler commented 9 years ago

It seems like the pin export helper doesn't like being called more than once. A workaround is to have a combined version of the cape as you implemented in #30.