Specify Linux CAN interface instance number

Technical Support
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1

After enabling two MCP2517FD CAN interfaces on two different SPIs on my Verdin I faced another problem.
ip a lists two CAN interfaces:

4: can0: <NOARP,ECHO> mtu 16 qdisc noop state DOWN group default qlen 10
    link/can 
5: can1: <NOARP,ECHO> mtu 16 qdisc noop state DOWN group default qlen 10
    link/can

Linux autoenumerates the interfaces, sometimes the can0 interface denotes ecspi2 CAN interface and sometimes ecspi3. Is it possible for user to manually enumerate CAN interfaces ?

@Edward suggested to use aliase in order to avoid Linux autoenumeration. I tried this:

aliases {
...
       /* ecspi2 CAN interface */
		can1 = &can3;
       /* ecspi3 CAN interface */
		can0 = &can1;
...
	};

But after rebooting Linux still autoenumerates CAN interfaces. Is there a way for me to manually reference ecspi3 as can0 and ecspi2 as can1 (or can5/6/7…) ?

P.S. It seemed like new problem so I opened new thread.

2

@gauravks did this for us, I think by setting their names in the devicetree. Then they should be fixed.

3

It seems I was wrong about it. Looks like CAN interface ordering is not supported in kernel. Somehow it works for i2c or serial…

Edward

4

Greetings @spasoye,

If device tree aliases don’t work, then perhaps we can try to implement a udev rule.

I found this post on the community that may help: How to fix the interface name of CAN on Colibri iMX6ULL - Technical Support - Toradex Community

Perhaps you can create a similar rule as what is show in this post. See if this lets you associate a can interface with a specific ecspi interface.

Best Regards,
Jeremias