Re: [PATCH 3.19-rc3] c_can: SIE disabled when berr-reporting is off to reduce irq flood

[Tom Evans <tom_usenet@optusnet.com.au>]

On 19/01/15 05:34, Marc Kleine-Budde wrote:
> On 01/18/2015 07:30 PM, Viktor Babrian wrote:
>>
>> Status interrupt is to be disabled if bus error reporting is off in order
>> to reduce interrupt flood when e.g. a frame is not acked. Side effect is
>> that when berr-reporting off, warn->pass and pass-warn state transitions
>> may be reported later (upon a successful rx/tx event) or even go
>> undetected. With proper implementation, these transitions could always be
>> detected (but still later). It is considered better to have a non-accurate
>> report of these transitions than having a non-responding system in
>> possible scenarios.
>>
>> Signed-off-by: Viktor Babrian <babrian.viktor@renyi.mta.hu>
>
> NACK. The transitions are important for some applications. I've an not
> yet mainlined series that limits the bus errors. I'm going to port them
> to the current kernel tomorrow. Can you test it?

Those "some applications" can enable "CAN_CTRLMODE_BERR_REPORTING" and get 
error reporting and prompt (and complete) state reporting.

Doesn't that answer your concern?

That approach was implemented in flexcan.c as per this patch:

 > Author: Wolfgang Grandegger <wg@grandegger.com>  2012-10-11 06:10:42
 > Committer: Marc Kleine-Budde <mkl@pengutronix.de>  2012-10-24 03:43:17

     can: flexcan: disable bus error interrupts for the i.MX6q

     This patch adds some Flexcan version info and removes the feature flag
     FLEXCAN_HAS_BROKEN_ERR_STATE for the i.MX6Q. It also has the line
     [TR]WRN_INT properly connected.

You approved this approach then (although possibly not knowing that that was 
what the patch was doing then).

Tom Evans