Re: [RFC PATCH] can: add tx/rx led trigger support

[Wolfgang Grandegger <wg@grandegger.com>]

On 04/12/2012 06:02 PM, Oliver Hartkopp wrote:
> On 12.04.2012 13:07, Martin Gysel wrote:
> 
>> Am 12.04.2012 09:37, schrieb Wolfgang Grandegger:
>>> Concerning the LED control (on. off, blinking), could that not be
>>> done/configured in the generic LED interface (via sysfs files)? That
>>> seems the right place for me. Then the CAN LED software just needs to
>>> send the trigger which would significantly simplify the code (without
>>> timer).
>>>
>>> Furthermore, if I understand your patch correctly, the LEDs with the
>>> names "canX-rx" and "canX-tx" are directly assigned (hardwired). A more
>>> flexible method would be appreciated, if it could be realized with just
>>> a little more code.
>>
>> maybe something familiar to the led netdev trigger (which is afaik
>> 'still' not mainline...)
>>
>> https://dev.openwrt.org/ticket/2776
> 
> 
> Hm - "still not in mainline" is not really nice.
> 
> I think the original approach from Fabio was to follow the LED implementation
> from mac80211:
> 
> "The implementation is similar to the MAC80211_LEDS one, and takes quite a lot
> of inspiration and some code from it."
> 
> And IMHO we should follow this implementation as it is proved to be used in
> high traffic netdev environments. I wonder if some 'generic gpio LED'
> implementation will perform sufficiently.

Yes, I agree. But that implementation does not use timers but toggles
the LED on/off for each new packet.

http://lxr.linux.no/#linux+v3.3.1/net/mac80211/led.c#L15

I would vote for that solution as well (because it's very lite and we
already have counters for rx and tx packets).

Wolfgang.