SPI not working after upgrade to ubuntu 18.04 with patched kernel from ppa

tdudz

Previously, I had ubuntu 16.04 with a patched 4.4 kernel and my code ran fine on the UP board, data being sent over SPI worked well.

I now upgraded to 18.04 and installed the patched kernel from the ppa and enabled spidev2.1 as a kernel boot param. I'm able to see /dev/spidev2.0 and /dev/spidev2.1, but when i run my code to communicate over SPI, i dont get any data back at all even though it succeeds in opening SPI.

What is the correct way to use SPI now? Did something change that I missed?

rreignier

I was able to use SPI on Ubuntu 18.04 with upboard kernel 4.15 from ppa.
But I have used it from a kernel driver (mcp2515) and not spidev.

tdudz

@rreignier said:
I was able to use SPI on Ubuntu 18.04 with upboard kernel 4.15 from ppa.
But I have used it from a kernel driver (mcp2515) and not spidev.

can you share more information about using the mcp2515 kernel driver? thx

rreignier

@tdudz said:
can you share more information about using the mcp2515 kernel driver? thx

Sure, I have used this module from @nukular https://forum.up-community.org/discussion/comment/9298/#Comment_9298 in a mcp2515_init.c file.
Then add a simple Makefile:

obj-m += mcp2515_init.o

all:
    make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

clean:
    make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

Then:

$ sudo apt install build-essential linux-headers-$(uname -r)
$ make
$ sudo insmod mcp2515_init.ko busnum=2 chip_select=1 gpio_int=25
$ sudo ip link set can0 up type can bitrate 500000