linux-kernel - Re: Vibrations in input vs. LED was Re: [PATCH v2 0/3] led: ledtrig-transient: add support for hrtimer

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Message-ID: <20170920111526.GA3097@amd>
Date:   Wed, 20 Sep 2017 13:15:26 +0200
From:   Pavel Machek <pavel@....cz>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>
Cc:     linux-input@...r.kernel.org, David Lin <dtwlin@...gle.com>,
        corbet@....net, rpurdie@...ys.net, hdegoede@...hat.com,
        gregkh@...uxfoundation.org, robh@...nel.org, romlem@...gle.com,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-leds@...r.kernel.org
Subject: Re: Vibrations in input vs. LED was Re: [PATCH v2 0/3] led:
 ledtrig-transient: add support for hrtimer

On Mon 2017-09-18 22:43:40, Jacek Anaszewski wrote:
> Hi,
> 
> On 09/17/2017 07:50 PM, Pavel Machek wrote:
> > Hi!
> > 
> >>>> Do you think such an improvement could be harmful in some way,
> >>>> even if it was made optional?
> >>>
> >>> Of course, we can make LED timing accurate down to microseconds. It will
> >>> mean increased overhead -- for "improvement" human can not perceive.
> >>>
> >>> If someone has problems with LED delays not being accurate enough... we
> >>> may want to fix it. But that is not the case here, is it?
> >>
> >> AFAIR David was mentioning that the hr_timer support is perceivable
> > 
> > He said that hr_timer support is perceivable _when he is driving
> > vibration motor_. Which he should not do in the first place.
> > 
> > Yes, if the difference is perceivable with LED in non-crazy
> > configuration (*), we can take the patch. Is it? Do we have someone
> > not from Google observing it?
> > 
> > (*) emulating PWM using blink trigger counts as "crazy" :-)
> 
> How about adding CONFIG_LED_TRIGGERS_HR_TIMER_SUPPORT, guarding the
> hr timer support in triggers (timer trigger could also benefit from it)
> with it, and adding "(EXPERIMENTAL)" tag to the config description?

Why would we want to add code in the LED subsystem that is useless for
LEDs?
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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