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

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

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On 16.02.2021 09:44:54, Torin Cooper-Bennun wrote:
> > Your mram-cfg looks broken, You don't have any TX Event FIFO entries. Please use
> > this one:
> >
> > bosch,mram-cfg = <0x0 0 0 16 0 0 1 1>;
> 
> Okay, thanks for the tip, I usually don't make use of the TX event
> feature!

You might not, but the driver does :)

> This hasn't fixed the TX behaviour, though. I've verified
> that the frame is loaded into MRAM and requested for TX correctly, but
> the transceiver does this...
> 
> 1. sends start-of-frame, then 5 bits of ID correctly, at the correct bitrate
> 2. bus then seems to be stuck dominant for 6 bits instead of
> transmitting further ID bits
> 3. bus lines drift back recessive (not a clean edge) over the duration
> of 12 bits
> 4. process repeats
> 
> Steps 2-3 constitute an error frame, if my understanding is correct.
> Presently the TCAN4550 is not connected to any other CAN nodes; I
> would therefore expect the transmit to at least continue to the ACK
> field.

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.

regards,
Marc

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