Hi Jacek, On Mon, Apr 24, 2017 at 12:59 PM, Jacek Anaszewski <jacek.anaszewski@xxxxxxxxx> wrote: > > 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. > I think I understand the background now, and would agree that not all the LED driver require hrtimer as human eye can't probably tell there's a 10ms variation in a blink. However, there's a need to support hrtimer if the LED subsystem claims support the use case of vibrator (please see Documentation/leds/ledtrig-transient.txt) as even a 5ms of variation is perceivable to the user. I'm thinking if a better interim solution is to introduce a LEDS_TRIGGER_TRANSIENT_HRTIMER config to work with both timers in compile time. Would you agree? David