Re: [PATCH] socketcan: add a driver for FlexCAN controllers.

Wolfgang Grandegger wrote:

On 06/18/2010 12:44 PM, Marc Kleine-Budde wrote:

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Wolfgang Grandegger wrote:

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On 06/18/2010 12:16 PM, Marc Kleine-Budde wrote:

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Wolfgang Grandegger wrote:

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Hi Hans-Jürgen,

On 06/17/2010 12:52 PM, Hans J. Koch wrote:

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This adds a driver for FlexCAN based CAN controllers,
e.g. found in Freescale i.MX35 SoCs.

The original version of this driver was posted by Sascha Hauer in July 2009:
http://kerneltrap.org/mailarchive/linux-netdev/2009/7/29/6251621

I took this version, added NAPI support, and fixed some problems found
during testing. Well, here is the result. Please review.

I briefly browsed the patch and various bits and pieces are missing or
not correctly implemented. Marc already pointed out a few of them:

- I do not find can_put/get_echo_skb functions in the code. How is
  IFF_ECHO supposed to work?

the driver uses hardware loopback

OK, then

  dev = alloc_candev(sizeof(struct flexcan_priv), 0);

should be used (and TX_ECHO_SKB_MAX removed) in Hans-Jürgens driver.

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- Support for CAN_CTRLMODE_BERR_REPORTING and do_get_berr_counter()
  seems to be missing.

- Make use of alloc_can_skb() and alloc_can_err_skb().

the last two points are already addressed in my version of the driver.

I do not see support for CAN_CTRLMODE_BERR_REPORTING in your driver
(which has nothing to do with do_get_berr_counter).

oh yes...sorry, got confused.

However I implemented CAN_CTRLMODE_BERR_REPORTING, i.e. turning of the
bit error interrupts by default. This has the effect that no bus warning
and bus passive interrupt was signalled.

I should add a comment to my driver.

I'm confused, CAN_CTRLMODE_BERR_REPORTING means that the user can enable
bus error reporting, which seems not be handled in the driver your sent.
See:

http://lxr.linux.no/linux/drivers/net/can/sja1000/sja1000.c#L134
http://lxr.linux.no/linux/drivers/net/can/sja1000/sja1000.c#L588

Which interrupts does "IRQ_BEI" include? What should
CAN_CTRLMODE_BERR_REPORTING do?

Looking at:
http://lxr.linux.no/linux+v2.6.34/drivers/net/can/sja1000/sja1000.c#L393
it seems that BEI on the SJA just effects bit, form and stuff errors.

If I disable the corresponding interrupt in the flexcan. This is
ERR_MSK, (1 << 14 in CTRL), I don't get error warning or error passive
interrupts either. I'm not sure about the bus off interrupt.

From my point of view this is not that what CAN_CTRLMODE_BERR_REPORTING
should do, is it?

Marc

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