Re: replacement for CAN_LEDS

From: Pavel Machek
Date: Mon Mar 11 2019 - 10:42:32 EST


> I'm in the process of upgrading an old BSP to a 4.19 kernel, and noticed
> that CAN_LEDS has been marked broken. The comments say that the netdev
> trigger can do everything, but doesn't provide much guidance on how to
> actually do the transition.

Seems like something to be improved.

> In my case, I used to have a device tree node
> canb {
> label = "canb:green:activity";
> gpios = <&gpio0 5 0>;
> default-state = "off";
> linux,default-trigger = "can1-rxtx";
> };
> and if I change the default-trigger to netdev, I get sysfs files in
> /sys/class/leds/canb:green:activity ; if I then echo can1 to device_name
> and 1 to rx,tx, and link, I get the behaviour I used to have.
> Questions: must this setup be done in userspace like this? Is there some
> udev rule template I could copy? I can also just hardcode the above
> dance in some init script.
> I'd actually prefer keeping the entire setup in device tree. So would it
> be possible to have netdev_trig_activate() look for some properties in
> the DT node for the led_classdev and populate ->device_name and ->mode
> based on them?

Sounds like good idea. Patch would be welcome...

(cesky, pictures)

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