Re: can, tcan4x5x: look to merge rpi support into rpi kernel tree

Marc Kleine-Budde
2021-02-16T11:20:47Z

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Please keep the mailing list on Cc.

On 16.02.2021 11:11:34, Torin Cooper-Bennun wrote:
> On Tue, 16 Feb 2021 at 10:28, Marc Kleine-Budde <mkl@pengutronix.de> wrote:
> > You might not, but the driver does :)
>
> Indeed, on closer inspection I can see that!
>
> > If the process repeats infinitely then the CAN controller doesn't go
> > into bus-off, which means the CAN bus is terminated correctly.
> >
> > With your setup of only one node on the bus and correct termination, I
> > too think the frame should be send until the ACK field. I suggest to
> > first create a working CAN bus setup and then add the tcan to it.
>
> I have to thank you for mentioning termination, because it turned out
> I had not used correct termination at all. How embarrassing! With that
> fixed, the transceiver is happy and I have working TX and RX.

\o/

> Mostly working RX, anyway. When putting the interface down and then
> back up (but allowing a second node to continue attempting TX in the
> meantime) I see some blank frames...
>
> can0 001 [8] 00 01 02 03 04 05 06 07
> can0 001 [8] 00 01 02 03 04 05 06 07
> can0 001 [8] 00 01 02 03 04 05 06 07
> can0 000 [0]
> can0 000 [0]
> can0 001 [8] 00 01 02 03 04 05 06 07
> can0 001 [8] 00 01 02 03 04 05 06 07
> etc.
>
> (where the 8-byte frame is what the bus is actually seeing.)

Where do you see these blank frames? On the sending rpi with candump? An
on the bus (with a second system) you only see the full 8 byte long
frames?

Use "candump any,0~0,#FFFFFFFF -extA" to get RX/TX annotation.
Use "cangen -Ii -L8 -D000102030405060708 -g100 can0" to get increasing
CAN-IDs, so you can figure out if a CAN frame got lost.

Seems I have to add the TX path to the list of broken things...

The mcp251xfd driver can be used as a template for the tcan4x5x driver.

regards,
Marc

--
Pengutronix e.K. | Marc Kleine-Budde |
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