Re: socketcan Features

Re: socketcan Features

[Marc Kleine-Budde]

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Hello,

some German questions, I'll answer here as these are quite interesting.

On 01/21/2016 12:05 PM, Uwe Koppe wrote:
> 1. Root Rechte
> 
> Wie kann man es erreichen, dass für die Konfiguration der CAN
> Schnittstelle (Bitrate, Up, Down, etc) keine Root
> Rechte erforderlich sind?

Q: Is it possible to configure the CAN interface without root permissions?

A: The capability CAP_NET_ADMIN should be sufficient. If not please
complain and/or send patches :)

> 2. Interrupts
> 
> Durch den Treiber werden CAN Error Interrupts „weitergereicht“, die
> in einigen Use-Cases das System langsam bis hin zu unbedienbar
> machen. Wie lassen sich CAN Interrupts konfigurieren ohne dass ich
> die Treiber anpassen muss?

Q: Driver pass CAN error interrupts to the userspace. On some systems
this leads to unresponsive systems.

A: You are probably using a flexcan IP core. On some SoCs the warning
interrupt is not attached to the interrupt controller. As a workaround
the error interrupts are enabled, which makes detection of the warning
interrupt possible again.

Another reason for bus errors reported to your application is tht you
have enabled bus error detection. If you need this, but don't want to be
flooded by them there's the feature called bus error limiting support
[1]. It's not mainline yet, but feedback is welcome.

regards,
Marc

[1] berr_limit support:
https://marc.info/?l=linux-can&m=138115684802850&w=2
https://marc.info/?l=linux-can&m=138115684802849&w=2
https://marc.info/?l=linux-can&m=138115684902851&w=2

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
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