How to enable SPI on Jetson Orin Nano Devkit

[noob502]

Hello,

I am building custom image for orin nano devkit using Yocto_Openembedded-core tools. And I am testing the SPI pins on 40 pin header.

Following SPI on Xavier NX, I have added into my local.conf

KERNEL_MODULE_AUTOLOAD += "spidev"
KERNEL_DEVICETREE_APPLY_OVERLAYS = "tegra194-p3668-all-p3509-0000-hdr40.dtbo"
IMAGE_INSTALL:append= " kernel-module-spidev spidev-test "

It is not working. I did not find tegra237-p3767-all-p3768-0000-hdr40.dtb into the tools.

I am on L4T 35.3 and meta-tegra kirkstone branch.

Morover I also tried to modify related dtb but I did not find them in running system

sudo cat /sys/kernel/debug/tegra_pinctrl_reg | grep -i spi
sudo cat /sys/kernel/debug/tegra_gpio

after running ls /proc/device-tree I got

 spi@3210000                                                                     
 spi@3230000                                                                     
 spi@3240000                                                                     
 spi@3250000                                                                     
 spi@3300000                                                                     
 spi@c260000 

I found the main dtb on running system /boot/tegra234-p3767-0003-p37668-0000-a0.dtb but did not find spi setting.

What is can be the solution ?

[madisongh]

The overlay you applied is specific to the Xavier NX; it wouldn't work for Orin devices. I think the correct overlay to use in your case is tegra234-p3767-0000-p3509-a02-hdr40.dtbo, although I haven't tested it myself. The name of the file implies that it's for use with the p3509 carrier, but from what I can tell, the pin assignments on that carrier and the p3768 carrier used in the Orin Nano dev kit are the same.

[madisongh]

It looks like the current pinctrl driver doesn't export those extra debugfs interfaces. They probably aren't needed any more.

[noob502]

I made a test script which should look for /dev/spidev* but there are nothing like this.

[noob502]

I also added spidev_test which supposed to be under tools/spidev_test but I found it on /usr/bin/spidev_test and it is also looking for /dev/spidev/ but it aborted as there is nothing like spidev* in /dev/

[madisongh]

Is the spidev kernel module loaded?

I've set this up on my Orin Nano dev kit with the following additions in my local.conf:

KERNEL_MODULE_AUTOLOAD:append = " spidev"
KERNEL_DEVICETREE_APPLY_OVERLAYS = "tegra234-p3767-0000-p3509-a02-hdr40.dtbo"
CORE_IMAGE_EXTRA_INSTALL = "kernel-module-spidev spidev-test"

These settings differ a bit from the ones in your original post.

This was for a build of the demo-image-base image out of the kirkstone branch of our demo distro. I flashed this to my dev kit, connected pins 19 and 21 on the 40-pin header, and ran:

# lsmod | grep spidev
spidev                 24576  0
# spidev_test -v -D /dev/spidev0.0
spi mode: 0x0
bits per word: 8
max speed: 500000 Hz (500 kHz)
TX | FF FF FF FF FF FF 40 00 00 00 00 95 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF F0 0D  |......@.........................|
RX | FF FF FF FF FF FF 40 00 00 00 00 95 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF F0 0D  |......@.........................|

to verify that it's working.

[noob502]

I built tegra-demo-distro and also got a similar result

# lsmod | grep spidev                             
spidev                 28672  0                                                 
# spidev_test -v -D /dev/spidev0.0                
spi mode: 0x0                                                                   
bits per word: 8                                                                
max speed: 500000 Hz (500 kHz)                                                  
TX | FF FF FF FF FF FF 40 00 00 00 00 95 FF FF FF FF FF FF FF FF FF FF FF FF FF|
RX | 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00|

But when I build with meta-tegra, meta-openembedded, and openembedded-core, I can not see the same result.

[madisongh]

Well, at least you have something working that you can compare against, to see what's set up wrong in your environment. The demo distro includes all of those layers, and doesn't really do any magic on top of that, so it's probably something pretty basic.

[noob502]

That's a good idea. I did a quick layer comparison, but it is not clear whether those layers are dependable. But I will look at them.