Re: [PATCH RFC V3.5] leds: trigger: Introduce an USB port trigger

[Pavel Machek <pavel@ucw.cz>]

On Mon 2016-08-29 10:21:48, Rafał Miłecki wrote:
> On 29 August 2016 at 10:05, Pavel Machek <pavel@ucw.cz> wrote:
> >> >2) Having "ports" subdir with RW files, one per each existing physical port
> >> >In this situation we don't need "new_port" or "remove_port". If we
> >> >want port to be observable we just do:
> >> >echo 1 > 1-1
> >> >Implementing this solution needs reading more details from USB subsystem.
> >>
> >> The situation here is clear IMO - the number of USB ports in the system
> >> can change dynamically. I'm not sure if this can be handled easily with
> >> sysfs, where we usually expose an interface for known set of settings.
> >> struct attribute arrays are usually defined statically at the compile
> >> time and filled with the variables, that are created with DEVICE_ATTR
> >> macro.
> >
> > sysfs already exposes current view of all usb devices. Just use it.
> 
> We're talking about USB ports not devices, but this is still true. You
> can find them in
> /sys/bus/usb/devices/*/*-port*
> 
> I can't see how we could use them. How could I develop sysfs interface
> in /sys/class/leds/*/ to allow userspace assigning USB ports to the
> LED trigger?

Create /sys/bus/usb/devices/*/*-port*/led_trigger file?

(Do you plan one USB trigger, or multiple ones?)
									Pavel

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