Re: [PATCH 0/5] can: mcp251xfd: workaround double-RX erratum

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

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On 11.01.2023 23:30:04, Marc Kleine-Budde wrote:
> On 11.01.2023 23:20:37, Marc Kleine-Budde wrote:
> > this is a proof of concept implementation to work around the
> > "double-RX" erratum found by Stefan Althöfer.
> > 
> > With the help of Thomas we found out that the chip has a time window
> > after receiving a CAN frame where the RX FIFO STA register content is
> > not read correctly.
> > 
> > From the driver's point of view, everything looks consistent at first,
> > but the head index of the chip is too large. This causes the driver to
> > rehandle old CAN frames that have already been processed.
> > 
> > The workaround uses the RX timestamp to distinguish between new and
> > old data. As soon as old data is found, processing is stopped.
> > 
> > The series applies against current net/main. The patches lack proper
> > descriptions, I'll add them in the next round.
> > 
> > Happy testing,
> > Marc
> > 
> > Link: https://lore.kernel.org/all/FR0P281MB1966273C216630B120ABB6E197E89@FR0P281MB1966.DEUP281.PROD.OUTLOOK.COM
> 
> If you add a "#define DEBUG" before any #includes in mcp251xfd-rc.c
> you'll get a debug message like this if the workaround triggers:
> 
> | Jan 11 22:53:10 riot kernel: mcp251xfd spi1.0 mcp251xfd0: mcp251xfd_handle_rxif_one: last_valid=0x17395fba3d56bb9c ts=0x17395fba3d08ee9e d=0xffffffffffb23302 data=00 02 80 fa 24 cc 43 41 - Dropping

In my over night test the workaround triggered 31 times. The test has
found no problems.

regards,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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