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: <9afbd987-b237-24d4-e16a-ddd7fa70766a@gmail.com>
Date:   Sun, 17 Sep 2017 18:41:33 +0200
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Pavel Machek <pavel@....cz>
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,

On 09/16/2017 03:58 AM, Pavel Machek wrote:
> 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?

AFAIR David was mentioning that the hr_timer support is perceivable

-- 
Best regards,
Jacek Anaszewski