Re: Writing socketCAN module for my own hardware

[Marc Kleine-Budde <mkl@pengutronix.de>]

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On 10/10/2014 09:43 AM, Florian Feldbauer wrote:
>>> Although I can see at the scope, that reading register 0 of the SJA1000
>>> returns the value 1 as it should be.
>>> Also, it seems that there is some kind of endless loop reading this
>>> register.
>> No, just a loop of up to 100 :)

> Maybe it's correlated with the issue that the message
> [  129.210423] sja1000_raspi sja1000_raspi.0 can0: bit-timing not yet
> appears over and over again in dmesg, but register 0 is definitely
> read more than 100 times...

As mentioned earlier, you have probably a mechanism running on your
system, that tries to enable the CAN interface. Bringing up the
interface without a set bit-rate is not allowed.

[...]

>>> Any Ideas why the first initialization of the kernel module doesn't
>>> work?
>>> When is the probe function of the module actually called?
>> As soon as there is a matching driver//device combination on a bus.
>> Looking at your driver, it's racy. You should not do any hardware setup
>> in the init function.
> Ok...I moved the whole configuration of the GPIOs into the probe
> function (instead of the init)
> and now it works! Thanks!
> 
> Now I only have to solve the problem, that bringing the interface down
> is not possible....
> Always need to reboot just to change bitrate is no fun.
> Maybe I should consult the Raspberry community, if there is some kind of
> network manager...

What kind of distribution are you using?

Marc

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