linux-kernel - Re: [PATCH v3 1/2] leds: core: Introduce generic pattern interface

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Message-ID: <20180718120836.GB23157@amd>
Date:   Wed, 18 Jul 2018 14:08:36 +0200
From:   Pavel Machek <pavel@....cz>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     Jacek Anaszewski <jacek.anaszewski@...il.com>,
        David Lechner <david@...hnology.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Mark Brown <broonie@...nel.org>,
        Linux LED Subsystem <linux-leds@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/2] leds: core: Introduce generic pattern interface

On Wed 2018-07-18 19:32:01, Baolin Wang wrote:
> On 18 July 2018 at 15:56, Pavel Machek <pavel@....cz> wrote:
> > Hi!
> >
> >> >>>>I believe I meant "changing patterns from kernel in response to events
> >> >>>>is probably overkill"... or something like that.
> >> >>>
> >> >>>Anyway -- to clean up the confusion -- I'd like to see
> >> >>>
> >> >>>echo pattern > trigger
> >> >>>echo "1 2 3 4 5 6 7 8" > somewhere
> >> >>
> >> >>s/somewhere/pattern/
> >> >>
> >> >>pattern trigger should create "pattern" file similarly how ledtrig-timer
> >> >>creates delay_{on|off} files.
> >
> > Yes, that sounds reasonable. v5 still says
> >
> > +               Writing non-empty string to this file will activate the pattern,
> > +               and empty string will disable the pattern.
> >
> > I'd deactivate the pattern by simply writing something else to the
> > trigger file.
> 
> For the case we met in patch 2, it is not related with trigger things.
> We just set some series of tuples including brightness and duration
> (ms) to the hardware to enable the breath mode of the LED, we did not
> trigger anything. So it is weird to write something to trigger file to
> deactive the pattern.

Confused. I thought that "breathing mode" would be handled similar way
to hardware blinking: userland selects pattern trigger, pattern file
appears (similar way to delay_on/delay_off files with blinking), he
configures it, hardware brightness follows the pattern ("breathing
mode"). If pattern is no longer required, echo none > trigger stops
it.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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