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

From: RafaÅ MiÅecki
Date: Mon Aug 29 2016 - 04:22:00 EST

On 29 August 2016 at 10:05, Pavel Machek <pavel@xxxxxx> 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

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?