Re: [Rfi] Cyclone V CAN errors when application pinned to CPU1

[Robert Schwebel <r.schwebel@pengutronix.de>]

Hi,


Adding Marc to Cc:.

On Fri, Oct 16, 2015 at 09:53:27PM +0200, Vlastimil Setka wrote:
> We discovered very weird behaviour of CAN controller in Cyclone V SoC
> with Linux socketcan stack. The problem was first seen on 3.10-ltsi a
> few months ago, and now again on 3.18 from altera github (with rt
> preempt patch applied).

Could you try if the issue happens with a recent mainline kernel as
well? RT is available for 4.1, so that would be a good choice.
 
> We have a linux application which sends data periodically (1 to 20 ms
> period) out over the can0 socketcan interface. Sometimes the first
> data byte in the CAN frame is zero on the wire, but non-zero in the
> data sent! When running with this period, this happens at random
> times, but during a few minutes it can be allways replicated.
> 
> The problem only appears when the application is pinned to CPU1 by
> linux process afinity mechanism. When pinned to default CPU0, there is
> no problem.
> 
> Anyone seen this issue? Any idea how to debug it and what can be a
> reason? What version (git repo / tag) of Linux should I use?
> 
> We plan to do some in-deep evaluation and testing, but I want to share
> the experience now.

Is your test program available somewhere?

Regards,
Robert Schwebel
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