lkml.org 
[lkml]   [2018]   [Oct]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v14 1/2] leds: core: Introduce LED pattern trigger
Hi Pavel,

On 11 October 2018 at 00:00, Pavel Machek <pavel@ucw.cz> wrote:
> Hi!
>
> [Oops. I wrote this but forgot to send it? Anyway.. I guess it is
> redundant now.]
>
>> > +++ b/Documentation/ABI/testing/sysfs-class-led-trigger-pattern
>> > @@ -0,0 +1,76 @@
>> > +What: /sys/class/leds/<led>/pattern
>> > +Date: September 2018
>> > +KernelVersion: 4.20
>> > +Description:
>> > + Specify a software pattern for the LED, that supports altering
>> > + the brightness for the specified duration with one software
>> > + timer. It can do gradual dimming and constant brightness.
>> > +
>> > + The pattern is given by a series of tuples, of brightness and
>> > + duration (ms). The LED is expected to traverse the series and
>> > + each brightness value for the specified duration. Duration of
>> > + 0 means brightness should immediately change to new value.
>> > +
>> > + 1. When doing gradual dimming, the led brightness will be updated
>> > + every 50 milliseconds, so the duration of each step should not
>> > + less than 50 milliseconds.
>>
>> I'd like to avoid this constraint. Lowest supported delta_t should be 1.
>>
>> We should only prevent entering dimming mode if current delta_t
>> is lower than UPDATE_INTERVAL.
>
> I agree that documenting it like this is strange. I don't think this
> should be part of ABI as we may want to adjust it in the future.
>
>> I also propose to make the dimming interval configurable via sysfs
>> dimming_interval file.
>
> I believe we should provide "right" dimming_interval. 50msec sounds
> good. If we find it is too low / too high, we might want to adjust it.
>
> If we find out that different users need different values, I guess we
> can still add "dimming_interval" knob, but I'd suggest waiting until
> such need arises.
>
> [Now, I don't have strong feelings here, and patch would probably be
> okay with me even if it has dimming_interval, but I'd prefer to keep
> it simple. We are at v14 of the patch...]

Make sense. I will leave this feature until someone has the
dimming_interval adjustment. Thanks.

--
Baolin Wang
Best Regards

\
 
 \ /
  Last update: 2018-10-11 04:06    [W:0.110 / U:0.080 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site