Re: [RFC][PATCH] net: arinc429: Add ARINC-429 stack

[Oliver Hartkopp <socketcan@hartkopp.net>]

On 11/03/2015 11:36 AM, Aleksander Morgado wrote:

> Unrelated to all this, another key point in ARINC is the timing for
> each label when transmitting. The common case you get is different
> labels being sent continuously with a given rate for each. E.g. labels
> 310 and 311 every 80ms, label 312 every 120ms and so on. I'm not sure
> the HOLT chips have any specific way of configuring this, but I've
> seen some USB devices which actually have APIs to say e.g. "send label
> 310 every 80ms" and then you can just update the value being sent
> without needing to take care of the TX rate. I'd have loved to see
> that instead of the complex filtering :) I know this is way too much
> for the generic kernel driver, though, so just a heads up of how this
> usually works.
> 

The CAN stack already has a solution for this.

The CAN_BCM socket is a programmable (content) filter for cyclic messages
which are common in automotive setups to detect timeouts in cyclic messages
(sender fails).

An the best thing: You can use the Linux internal high-res timers to send
messages - just by creating a TX_SETUP configuration for the BCM.

Read this:
https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/tree/Documentation/networking/can.txt?h=linux-4.2.y#n634

Just one more reason to use PF_CAN :-)