From: Pavel Machek <pavel@ucw.cz>
To: Phil Sutter <phil@nwl.cc>
Cc: linux-leds@vger.kernel.org
Subject: Re: [PATCH] leds: trigger: Add invert attribute to ledtrig-audio
Date: Tue, 10 Aug 2021 15:52:43 +0200 [thread overview]
Message-ID: <20210810135243.GB28089@amd> (raw)
In-Reply-To: <20210810092246.GB3673@orbyte.nwl.cc>
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Hi!
>
> On Mon, Aug 09, 2021 at 08:11:18PM +0200, Pavel Machek wrote:
> > > Inverting micmute LED used to be possible via a mixer setting, but
> > > conversion to LEDs class (probably) killed it. Re-establish the old
> > > functionality via sysfs attribute in audio LED triggers.
> >
> > So we have both invert and inverted attributes. Fun :-).
>
> Hmm! :)
>
> Are you talking about LED_BLINK_INVERT flag? I see a few triggers allow
> inversion but didn't find LED drivers exporting such a property.
>
> > See sysfs-class-led and sysfs-class-led-trigger-oneshot.
>
> I think I "copied" from oneshot trigger when writing this patch.
>
> > We definitely want this documented. We probably want this for most
> > triggers, maybe it should get one implementation in library somewhere?
>
> Should this be an implicit attribute of simple triggers only or all? In
> the latter case (which could simplify some triggers) I guess the value
> inversion has to take place in led_set_brightness_nopm(), the lowest
> level function triggers may use.
Actual inversion is trivial (so it may not make sense to share), but
sysfs interface is not. Sharing that would be good.
> How does inversion work, actually? LED_OFF <-> LED_ON is trivial, but
> what about LED_HALF and LED_FULL? Leaving LED_HALF as-is seems logical,
> but the opposite of LED_OFF might be LED_ON or LED_FULL. Does
> max_brightness determine that?
max_brightness determines that, and it would be simply
if (->inverted)
b = ->max_brighntess-b;
Best regards,
Pavel
--
http://www.livejournal.com/~pavelmachek
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prev parent reply other threads:[~2021-08-10 13:52 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-09 12:29 [PATCH] leds: trigger: Add invert attribute to ledtrig-audio Phil Sutter
2021-08-09 18:11 ` Pavel Machek
2021-08-10 9:22 ` Phil Sutter
2021-08-10 13:52 ` Pavel Machek [this message]
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