Re: [RFC PATCH 00/14] can: netlink: add CAN XL

[Oliver Hartkopp <socketcan@hartkopp.net>]

On 11.11.24 16:17, Vincent Mailhol wrote:
> On 11/11/2024 at 23:08, Oliver Hartkopp wrote:
>> Hello Vincent!
>>
>> Very impressive! Thanks for the effort.
>> Together with the example in the dummyxl driver it should become quite 
>> easy to integrate the netlink API into my XCANB driver hack for testing.
>>
>> Picking up the dummyxl driver I wonder if it would make sense to 
>> mainline this driver probably as can_nltest driver?!?
>> Of course this driver should be disabled or combined with some kernel 
>> testing Kconfig stuff. But is it a great testing tool.
> 
> Thanks. I do not recall similar things in the netdev subtree. I wonder 
> what would be the idiomatic way to introduce such netlink test driver.
> 
> @Marc, any thoughts on this?
> 
>> From what I can see with the bitrate and tdc configurations the 
>> extension for CAN XL is ok.
>>
>> If you take a look at this manual
>>
>> https://github.com/linux-can/can-doc/blob/master/x_can/ 
>> xcan_user_manual_v350.pdf
>>
>> on page 268/304 you will find the PWM configuration which consists of 
>> three values with 6 bits each. I assume this to be similar in all CAN 
>> XL controllers.
>>
>> The PWM feature switches the physical layer for a CAN XL transceiver 
>> in the CAN XL data phase. This is a weird feature to do some PWM on 
>> the controllers' TX data pin to be able to switch the physical layer 
>> while maintaining the CAN transceiver package with 8 pin layout.
>>
>> Additionally to this PWM configuration register, the PWM CAN XL 
>> transceiver switch feature has to be enabled similar to the way we 
>> enable 'fd on' or 'xl on' today.
>>
>> You can see this bit called XLTR in the Operating Mode section on page 
>> 269/304 and 270/304 .
>>
>> E.g. that might be named 'xltrx [on|off]' (default off)
> Thanks for the information and the link to the documentation. I will 
> also try to see what ISO 11898-1:2024 has to say on the topic. Just be 
> patient on this and do not worry if I give no signal for a couple weeks.

No problem! I will give some feedback when I managed to integrate the 
extended netlink API to my driver.

Maybe Robert also gets his hands on this, so that we can continue to 
discuss things even when you are busy for some time.

Best regards,
Oliver