Confused about CAN stuff: mttcan, mttcan-ivc and nvhvseccan - DRIVE 4.1.8.0

[hartkopp]

Hi Josep,

thanks for your answers!

@Josep

Here some answers to your questions (the answers are mostly taken from Vibrante for Linux documentation, as you pointed above http://docs.nvidia.com/drive/nvvib_docs/index.html in the CAN section):
1. How can I use the time triggered functionality of the MTTCAN (examples/documentation)?
Set up and usage of MTTCAN is as follows.
(…)

Sorry if I unclearly expressed myself. Of course I read the documentation and setting the bitrate is no problem for me.

The difference between the MCAN IP core and the MTTCAN IP core which is integrated in the Tegra SoC is the possibility to make the controller act as a time triggered master or slave node following ISO 11898-4 see e.g. Time-Triggered Protocol - Wikipedia .

So my question was about how to use this specific “time triggered” mode of the MTTCAN driver? Are there any examples/documentations?

@Josep

2. Are TegraA (can1) and TegraB (can0) connected anywhere?

Tegra-A and Tegra-B are inter-connected with Ethernet over the Marvell Gb AVB Switch.

I had a CAN related question, I’ll try to reorder:

• Is can1 from Tegra A connected anywhere?
• Is can0 from Tegra B connected anywhere?

I know this connection:

Tegra A can0 → CAN5
Tegra B can1 → CAN6

But Tegra A can1 and Tegra B can0 both seem not to be connected at all.

@Josep

3. Why are the bitrates (CAN/CAN FD) restricted in mttcan in comparison to the m_can driver in mainline Linux?

125000(125 Kbps), 250000(250 Kbps), 500000(500 Kbps) and 1000000(1Mbps) are supported bitrates for Tegra MTTCAN driver.
Any other bitrate is not validated on Tegra MTTCAN driver.

My question was WHY did you made these restrictions? IMO there’s no reason for that.

@Josep

Only 500000 (500 Kbps) bitrate is supported for Tegra MTTCAN-IVC. Other bitrates are not enabled on Tegra MTTCAN-IVC driver out of box. Details are available in the SPE documentation.

What means “SPE documentation”? Where can I find it?

@Josep

4. What is the intention of mttcan-ivc driver module? Does it make AURIX CAN interfaces SocketCAN interfaces on the Tegra (which would be cool)? How can they be configured and used?
mttcan-ivc that uses CAN driver services through IVC and implemented in SPE-FW. This driver can potentially be used by both SPE firmware and Linux.

I read this sentence in the documentation too. But I still don’t know how this Linux/SPE-FW setup looks like, whether it provides a SocketCAN interface on the Tegra and how I can make the mttcan-ivc driver WORK on a real CAN bus?

So in fact all my questions are still unanswered … :-/

Thanks & best regards,
Oliver