Colibri T30 on eval board - how to config for CAN

Technical Support
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#1

Hi,
I am having trouble configuring the CAN bus working on the Colibri T30 on the evaluation board (V3.2B). I’ve built and installed the angstrom-lxde-image on the board.

ip link doesn’t show the can0 device, so the MCP2515 driver seem not to be installed:

root@colibri-t30:~# ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN mode DEFAULT group default 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: dummy0: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN mode DEFAULT group default 
    link/ether be:31:69:c2:78:cd brd ff:ff:ff:ff:ff:ff
3: eth0: <BROADCAST,MULTICAST,DYNAMIC,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 00:14:2d:29:00:ac brd ff:ff:ff:ff:ff:ff
4: ip6tnl0: <NOARP> mtu 1452 qdisc noop state DOWN mode DEFAULT group default 
    link/tunnel6 :: brd ::
7: rndis0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state UNKNOWN mode DEFAULT group default qlen 1000
    link/ether 8a:9f:04:ed:57:e3 brd ff:ff:ff:ff:ff:ff

root@colibri-t30:~# zcat /proc/config.gz | grep CONFIG_CAN
# CONFIG_CAN is not set
root@colibri-t30:~#

The documentation suggests adding these definitions:

CONFIG_CAN=y
CONFIG_CAN_RAW=y
CONFIG_CAN_BCM=y
CONFIG_CAN_DEV=y
CONFIG_CAN_MCP251X=y

Where is the place to add these definitions ?

#2

What exact hardware (module and carrier board) and software versions of things are you talking about?

Those definitions would need to be added to its kernel configuration arch/arm/configs/colibri_t30_defconfig. And then you would need re-building the kernel as explained in the following article on our developer website:

#3

Thanks for the quick reply.

The hardware is a Colibri T30 on a Colibri Evaluation Board (V3.2B) and the OS is OpenEmbedded (Angstrom v2017.12 - Kernel, Colibri-T30_LXDE-Image 2.8b6).

I am already able to compile my own kernel with some custom layer, all derived from the toradex LXDE image (toradex branch LinuxImageV2.8). But I am unable to find a way in the yocto framework to modify/append the necessary flags to the defconfig from within my own layer. Of course, I could just edit the mentioned defconfig or the toradex layer, but this is not very portable.

#4

Ah, OK. So you do have CAN working already if manually compiled, right?

Then, you may want to have a look at the following recipe you may adopt as a bbappend in your own layer:

http://git.toradex.com/cgit/meta-toradex-tegra.git/tree/recipes-kernel/linux/linux-toradex_git.bb?h=rocko#n21

Makes sense?

#5

Yes it makes sense, although I was hoping of a “more elegant” approach. Thanks again.

#6

What “more elegant way” are you looking for?