linux-kernel - Re: [PATCH] led: ledtrig-transient: replace timer

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Date:   Thu, 27 Apr 2017 20:37:10 +0200
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     David Lin <dtwlin@...gle.com>
Cc:     rpurdie@...ys.net, pavel@....cz, robh@...nel.org,
        Rom Lemarchand <romlem@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>, stable@...r.kernel.org,
        linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] led: ledtrig-transient: replace timer_list with hrtimer

On 04/27/2017 05:48 AM, David Lin wrote:
> On Tue, Apr 25, 2017 at 1:15 PM, Jacek Anaszewski
> <jacek.anaszewski@...il.com> wrote:
>>> 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?
>>
>> I think that it would be better if LED class driver set a flag
>> marking itself as capable of setting brightness with high rate.
>> I'd limit that only to leds-gpio and devices driven through
>> memory mapped registers.
>>
>> Having the flag e.g. LED_BRIGHTNESS_FAST, we could add support for
>> hr timers also to ledtrig-timer.
> 
> Can I resubmit the patch implementing LED_BRIGHTNESS_FAST using hrtimer?

Yeah, but please split the changes into two patches:

1/2 - addition of a flag to linux/leds.h and corresponding update of
      Documentation/leds/leds-class.txt
2/2 - addition of hr timer support to ledtrig-transient.c

-- 
Best regards,
Jacek Anaszewski