On Thu, Sep 06, 2012 at 10:57:28PM +0200, Fabio Baltieri wrote:

On Thu, Sep 06, 2012 at 05:11:58PM +0200, Kurt Van Dijck wrote:

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I also think that led triggers should be available.

Right, that's why I think the only way is to use device name.

yes, but it has 2 disadvantages:
* inconvenient. I like 'can0-tx' much more than any device name
  (Sorry I can't get any real example, I'm not at home now).
  And for usecases where the actual device of the CAN iface is
  important, such setup requires udev to assign the proper iface names.

Can't argue with that... I'm trying to see how it comes but names like
"can-3-2:1.0-tx" doesn't looks that friendly to me...

"can-3-2:1.0" is an iface name?
We must keep default iface names can%d. Only in the usecase that someone
wants to name its ifaces according device names, he/she should manually
adjust udev rules on his/her system ...

And if the iface is names "can-3-2:1.0", "can-3-2:1.0-tx" _is_
a friendly trigger name.

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* extends existing function calls like sja1000

Indeed.

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I asked the question because detach & attach leds to interfaces would
indeed break that.

Sure? I think that the trigger would be set again on reattach, as
default_trigger is checked both in led_cdev probe and
trigger_register, see:

http://lxr.free-electrons.com/source/drivers/leds/led-triggers.c#L180

I'll try that tonight.

It looks even more inconvenient. It only works as expected when you don't
change the trigger afterwards, but still it is possible (as should be),
so the design of trigger is ... wrong.
example:
When you put another trigger to a led, and have a proper sequence of
'ip link set xxx up' and 'ip link set xxx down', you will end up
with the default_trigger again.
I realize I'm looking at unusual scenario's.

That's not correct, default trigger is going to be set only if there are
no other trigger assigned to the LED, and only on led probe and trigger
probe.

So, the LED framework is not going to change the trigger if you manually
changed it to something else, and in any case default_trigger assignment
only happens at probe/exit, not when interface is set up/down.

I think you're also arguing against a register/unregister during iface up/down.
We agree.

Kurt