Re: [PATCH v5] can: flexcan: Re-write receive path to use MB queue instead of FIFO

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

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On 10/06/2014 09:28 AM, David Jander wrote:
>>> 2.- Since the problem addressed by my patch to at91_can is very similar,
>>> what about solving these problems in the SocketCAN framework (if that is
>>> possible)?
>>
>> Have you had a look at my rx-fifo branch in
>> https://gitorious.org/linux-can/linux-can-next? It already tries to
>> abstract the simulation of the FIFO with the linear mailboxes.
> 
> Looks interesting. I think it is a good idea to do this in dev.c, since there
> are obviously more CAN drivers that can use this. Unfortunately it seems you
> are still pretending the napi-poll handler to call can_rx_fifo_poll().
> Wouldn't it be better to just empty all MBs into a circular buffer or kfifo
> from the interrupt handler instead?

Yes probably, I started the rx-fifo patch before you came up with that idea.

> I still don't understand the results Alexander is getting, though....
> 
> What are you going to do with the rx-fifo work? Do you recommend to base my
> patch on that? In that case, calling can_rx_fifo_poll() from the interrupt
> handler will look a little awkward... but it should work. Or should I propose
> an extension to rx-fifo?

My plans, or rather the points that need to be addressed for the rx-fifo
are:
- improve to work with more than 32 mailboxes. 64 are probably enough
  for everybody :)
- make it work with the flexcan linear buffers
- make it work with the ti_hecc driver
- add option or convert to run from interrupt handler and copy to
  kfifo/cyclic buffer/...

Marc

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