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Re: [PATCH] led: ledtrig-transient: replace timer_list with hrtimer

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Hi!
> Hi David,
> 
> Thanks for the patch.
> 
> Unfortunately we cannot switch to using hr timers just like that
> without introducing side effects for many devices. We had similar
> attempt of increasing timer tirgger accuracy two years ago [0].
> 
> In short words, for drivers that can sleep while setting brightness
> and/or are using a bus like I2C you will not be able to enforce
> 1ms delay period.
> 
> I recommend you to go through the thread [0] so that we had
> a well defined ground for the discussion on how to address this
> issue properly.
> 
> Alternatively, in order to avoid all quirks related to LED subsystem,
> I'd propose to implement this feature in the GPIO subsystem, which
> seems to be more suitable place for it.

Actually.. make that "implement it in force feedback subsystem where
it belongs". And we actually have force feedback subsystem, already,
see drivers/input/ff-core.c .

(Nokia N900 actually uses that subsystem for the vibration motor, so
there's existing code...)

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

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[PATCH] led: ledtrig-transient: replace timer_list with hrtimer David Lin <dtwlin@google.com> - 2017-04-24 06:50 +0200
  Re: [PATCH] led: ledtrig-transient: replace timer_list with hrtimer Pavel Machek <pavel@ucw.cz> - 2017-04-24 09:50 +0200
  Re: [PATCH] led: ledtrig-transient: replace timer_list with hrtimer Jacek Anaszewski <jacek.anaszewski@gmail.com> - 2017-04-24 22:10 +0200
    Re: [PATCH] led: ledtrig-transient: replace timer_list with hrtimer Pavel Machek <pavel@ucw.cz> - 2017-04-24 22:20 +0200
    Re: [PATCH] led: ledtrig-transient: replace timer_list with hrtimer David Lin <dtwlin@google.com> - 2017-04-25 05:10 +0200
      Re: [PATCH] led: ledtrig-transient: replace timer_list with hrtimer Jacek Anaszewski <jacek.anaszewski@gmail.com> - 2017-04-25 22:20 +0200
        Re: [PATCH] led: ledtrig-transient: replace timer_list with hrtimer David Lin <dtwlin@google.com> - 2017-04-27 05:50 +0200
          Re: [PATCH] led: ledtrig-transient: replace timer_list with hrtimer Jacek Anaszewski <jacek.anaszewski@gmail.com> - 2017-04-27 20:40 +0200
      Re: [PATCH] led: ledtrig-transient: replace timer_list with hrtimer Pavel Machek <pavel@ucw.cz> - 2017-04-26 00:40 +0200
        Re: [PATCH] led: ledtrig-transient: replace timer_list with hrtimer Jacek Anaszewski <jacek.anaszewski@gmail.com> - 2017-04-26 22:00 +0200

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