Hi Pavel, On 11 October 2018 at 00:00, Pavel Machek <pavel@xxxxxx> 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
