From mboxrd@z Thu Jan  1 00:00:00 1970
From: Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH RFC V3.5] leds: trigger: Introduce an USB port trigger
Date: Mon, 29 Aug 2016 10:41:27 +0200
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Cc: Jacek Anaszewski <j.anaszewski@samsung.com>, Jacek Anaszewski <jacek.anaszewski@gmail.com>, Alan Stern <stern@rowland.harvard.edu>, Richard Purdie <rpurdie@rpsys.net>, Felipe Balbi <balbi@kernel.org>, Greg KH <gregkh@linuxfoundation.org>, Peter Chen <hzpeterchen@gmail.com>, "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>, =?utf-8?B?UmFmYcWCIE1pxYJlY2tp?= <rafal@milecki.pl>, Jonathan Corbet <corbet@lwn.net>, Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>, Stephan Linz <linz@li-pro.net>, Matthias Brugger <mbrugger@suse.com>, Boris Brezillon <boris.brezillon@free-electrons.com>, Geert Uytterhoeven <geert@linux-m68k.org>, "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>, open list <linux-kernel@vger.kernel.org>"open list:LED SUBSYSTEM" <l>

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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