Re: [PATCH 4/4] can: flexcan: Disable error irq when in error passive

[Alexander Stein <alexander.stein@systec-electronic.com>]

On Thursday 14 August 2014 15:58:19, Marc Kleine-Budde wrote:
> On 08/14/2014 03:19 PM, Alexander Stein wrote:
> > On Thursday 14 August 2014 13:18:47, Marc Kleine-Budde wrote:
> >> On 08/12/2014 03:43 PM, Alexander Stein wrote:
> >>> If the error irq is enabled and the hardware is trying to send a CAN
> >>> message to an open bus it will receive a lot of acknowledge errors and
> >>> generating lots of interrupts. So error interrupts are disabled when
> >>> entering error passive and reenable them when leaving error passive.
> >>> We can only leave error passive by receiving CAN frames in which case NAPI
> >>> is scheduled anyway or by sending more CAN frames when send is possible
> >>> again. But with the transition of error counters from 96 to 95 the flags
> >>> TX_WRN and RX_WRN are gone again, so we need to remember the flags state
> >>> to detect a change there.
> >>
> >> There are use cases where the error interrupts even when in passive mode
> >> are essential. You have a use case, where you'd like to turn them off
> >> completely. Have you had a look at the bus error limiting patches?
> > 
> > Do you mean "[PATCH v7] flexcan: add err_irq handler for flexcan" from Zhao Qiang?
> 
> No, sorry I assumes you were following the discussion with Matthias
> Klein and Sebastian Andrzej Siewior [1].
> 
> I was talking about the patch from
> http://comments.gmane.org/gmane.linux.can/4070
> 
> The idea behind this series is to not enable the bus error interrupt
> right after it has served, but after a configurable delay, e.g. 100ms.
> Even with an open or otherwise faulty but, you then receive just 10
> error frames per second.
> 
> Marc
> 
> [1] http://thread.gmane.org/gmane.linux.can/6271
> [2] http://thread.gmane.org/gmane.linux.can/6280

I didn't follow this thread. I mostly used the flexcan driver but noticed now some hickups.

Regards,
Alexander
-- 
Dipl.-Inf. Alexander Stein

SYS TEC electronic GmbH
Am Windrad 2
08468 Heinsdorfergrund
Tel.: 03765 38600-1156
Fax: 03765 38600-4100
Email: alexander.stein@systec-electronic.com
Website: www.systec-electronic.com
 
Managing Director: Dipl.-Phys. Siegmar Schmidt
Commercial registry: Amtsgericht Chemnitz, HRB 28082