hardware hack Cubietruck Allwinner A20 SPIDEV - no such device

[fri40]

Hi there.

Trying to get SPIDEV working on my good old cubietruck aka cubieboard3 with an allwinner A20. Found some posts here and there dealing with A20 boards. But nothing of that did anything for me so far.

 

1. Enabled it in armbian-config hardware settings and rebooted. No /dev/spi* at all. No mentioning of "spi" in dmesg.
2. Step 1 gave a line "overlays=spi-spidev" in /boot/armbianEnv.txt. Read somewhere else that there should be another line "param_spidev_spi_bus=0", but that was not created by armbian-config.
3. Added that ...bus=0 line myself and rebooted. Still no spi device and nothing in dmesg

 

/proc/device-tree-model says "cubietech cubietruck" which is correct.

 

Running 5.4.20-sunxi, fresh install a few days ago. Nothing special done to it yet.

 

Anyone still playing with these old toys and done this?

 

Thanks!

 

[fri40]

Some progress... after many hours of strolling through various threads on SPI issues from about 200 before Christ up to about 2018....

1. Found some tweaks to the device tree files and the spi-spidev overlay which got me a /dev/spidev0.0.
2. Then tried a loopback test with spidev_test.c from the kernel sources.
3. That gave lots of ouput TX, but only zeros on RX.
4. Reverted changes, tried this and that.
5. Eventually ran apt update + apt upgrade to get the kernel from 5.4.20-sunxi to 5.4.35-sunxi.
6. After a reboot, this makes spidev0.0 appear without any of my earlier tweaks to the device tree / overlay files.
7. But I still can't get spidev_test.c get anything back to itself but zeros (i.e. "nothing")

I'm sure I have the right pins looped - unless every documentation I find on the cubieboard3 / cubietruck layout is wrong (guess not).

Also the wire (10cm) connects the pins - checked; they are at least "shortend" to each other by it.

 

Anyone out there who recently got spidev working on an allwinner a20? All those I found who did it did so years back doing more or less the same I did. They got their /dev/spidev0.0 appearing, fired up the loop test and were happy (as it seems).

 

H E L P :-) !