Re: [PATCH RESEND 15/16] leds: add LM3633 driver

[Jacek Anaszewski]

Hi Milo,

On 11/23/2015 12:40 AM, Kim, Milo wrote:
> Hi Jacek,
>
> On 11/20/2015 6:22 PM, Jacek Anaszewski wrote:
> > On 11/10/2015 08:38 AM, Kim, Milo wrote:
> > [...]
> > > > > +                cat /sys/class/leds/<led>/pattern_levels
> > > > > +                low brightness: 0, high brightness: 255
> > > > > +
> > > > > +What:        /sys/class/leds/<led>/run_pattern
> > > > > +Date:        Oct 2015
> > > > > +KernelVersion:    4.3
> > > > > +Contact:    Milo Kim <milo.kim@xxxxxx>
> > > > > +Description:    write only
> > > > > +                After 'pattern_times' and 'pattern_levels' are
> > > > > updated,
> > > > > +                run the pattern by writing 1 to 'run_pattern'.
> > > > > +                To stop running pattern, writes 0 to 'run_pattern'.
> > > >
> > > > I wonder how registering an in-driver trigger would work. It would
> > > > allow for hiding above pattern attributes when the trigger is inactive,
> > > > and thus making the sysfs interface more transparent. You could avoid
> > > > the need for run_pattern attribute, as setting the trigger would itself
> > > > activate the pattern, and setting brightness to 0 would turn it off.
> > >
> > > I like this idea, let me try to fix it.
> >
> > After thinking it over, I came to conclusion that implementing it as
> > an in-driver trigger is not a proper way to go, since triggers are
> > defined as kernel based source of LED events.
> >
> > This is somehow abused in case of timer trigger which takes hardware
> > blinking feature as a first choice and applies software blinking as
> > a fallback only. To be consistent with that, we could go for adding
> > generic pattern trigger and add a led_pattern_set() API, similarly
> > to existing led_blink_set().
> >
> > The problem is that different LED controllers may implement blinking
> > patterns that are configured with different set of parameters. This
> > subject would definitely require thorough analysis.
> >
> > For now, please just expose pattern settings as separate sysfs
> > attributes of a LED class device.
>
> Thanks for your suggestion.
> Then, LM3633 LED driver will support 8 device attributes.
>
>      pattern_time_delay
>      pattern_time_rise
>      pattern_time_high
>      pattern_time_fall
>      pattern_time_low
>      pattern_brightness_low
>      pattern_brightness_high
>      pattern_run_pattern
>
> Details will be updated in
> Documentation/ABI/testing/sysfs-class-led-lm3633.

OK, it looks reasonable.

--
Best Regards,
Jacek Anaszewski
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