linux-kernel - Re: [PATCH v3 3/3] leds: trigger: implement a tty trigger

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Message-ID: <20191217172102.GB3829986@kroah.com>
Date:   Tue, 17 Dec 2019 18:21:02 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Cc:     Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Pavel Machek <pavel@....cz>, Dan Murphy <dmurphy@...com>,
        Jiri Slaby <jslaby@...e.com>, kernel@...gutronix.de,
        linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org,
        linux-serial@...r.kernel.org
Subject: Re: [PATCH v3 3/3] leds: trigger: implement a tty trigger

On Tue, Dec 17, 2019 at 05:23:13PM +0100, Uwe Kleine-König wrote:
> On Tue, Dec 17, 2019 at 04:27:24PM +0100, Greg Kroah-Hartman wrote:
> > On Tue, Dec 17, 2019 at 04:07:36PM +0100, Uwe Kleine-König wrote:
> > > Usage is as follows:
> > > 
> > > 	myled=ledname
> > > 	tty=ttyS0
> > > 
> > > 	echo tty > /sys/class/leds/$myled/trigger
> > > 	cat /sys/class/tty/$tty/dev > /sys/class/leds/$myled/dev
> > 
> > Is this the correct instructions?  Aren't you looking for a major/minor
> > number instead in your sysfs file?
> 
> This is correct, yes, at least it works as intended on my machine.
> 
> /sys/class/tty/$tty/dev produces $major:$minor and that's what the
> led-trigger consumes.

Ugh, nevermind, I totally read that wrong, I was thinking "echo" instead
of cat.  My fault, what you wrote is correct.  Should that be documented
somewhere in a Documentation/ABI/ file so that people know how to use
this new sysfs file?  How are led triggers documented?

thanks,

greg k-h