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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Date:   Sat, 16 Sep 2017 03:58:10 +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

Hi!

> >>>> These patch series add the LED_BRIGHTNESS_FAST flag support for
> >>>> ledtrig-transient to use hrtimer so that platforms with high-resolution timer
> >>>> support can have better accuracy in the trigger duration timing. The need for
...
> > If we want to say "lets move all vibrations from input to LED
> > subsystem"... I don't think that is good idea, but its a valid
> > discussion. Some good reasons would be needed.
> > 
> > But having half devices use one interface and half use different one
> > is just bad... especially when only reason to do it that way is
> > "David wants to do it that way, android library made a mistake and he
> > now wants it to propagate to whole world".
> 
> This is not the only reason. Adding hr_timer support to
> ledtrig-transient (and similarly to ledtrig-timer) would allow
> to increase the accuracy and stability of delay_on/delay_off
> intervals at low values.
> 
> 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?
								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html