Re: [PATCH v2 1/2] leds: Add Intel Cherry Trail Whiskey Cove PMIC LEDs

[Hans de Goede]

Hi,

On 2/17/19 1:08 AM, Pavel Machek wrote:
> > > I don't pretend to fully understand it, _but_ hw_pattern should really
> > > describe the pattern LED should do, not whether it reacts to charging
> > > or not.
> >
> > Then we are back to step 1 of the discussion, that we need another
> > mechanism outside of the trigger to select if the LED shows the configured
> > pattern always, or only when the charger is on.
>
> Yep, sorry.
>
> > These really are 2 orthogonal settings, there is a pattern which can
> > be set and the LED can either show that pattern always; or only when
> > charging the battery. Note that the same pattern is used in both cases.
> >
> > This is why I previously suggested having a custom sysfs hardware_control
> > attribute which selects between the "only show pattern when charging"
> > modes ("hardware_control=1" or "always show the pattern mode"
> > ("hardware_control=0").
>
> I see... and yes, that would be the easiest solution.
>
> But somehow I see "this LED is controlled by charging state" as
> primary and "it shows pulses instead of staying on" as secondary
> eye-candy.
>
> This week there was another driver for charger LED.. but that one does
> not do pulses. Ideally, we'd like consistent interface to the
> userland.
>
> (To make it complex, the other driver supports things like:
>    LED solid on -- fully charged
>    LED blinking slowly -- charging
>    LED blinking fast -- charge error
>    LED off -- not charging).

Something like that could be supported with my original hw_pattern
proposal where we simply encode all of this in the hw-pattern file:

tupple0: charging blinking_on_time
tupple1: charging blinking_off_time
tupple2: charging breathing_time
tupple3: manual blinking_on_time
tupple4: manual blinking_off_time
tupple5: manual breathing_time

So for this chip you mention, we do not need the breathing time (no breathing support),
so we would get the following tupples:

tupple0: not charging blinking_on_time
tupple1: not charging blinking_off_time
tupple2: slow charging blinking_on_time
tupple3: slow charging blinking_off_time
tupple4: fast charging blinking_on_time
tupple5: fast charging blinking_off_time
tupple6: charging error blinking_on_time
tupple7: charging error blinking_off_time

Where by solid on/off can be done by setting one
of the blinking times to 0.

Having hw_pattern ABIs like this where some of
the tupples only activate on certain conditions
might be better then a hardware_control sysfs
file as it offers more flexibility.

Regards,

Hans