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SubjectRe: [PATCH v3 1/2] dt: bindings: lm3692x: Add bindings for lm3692x LED driver

> >> If that does not yet exist... you want to create glue layer to be able
> >> to use LED as a display backlight. (It may already exist, no idea).
> >>
> >> ...
> >>
> >> Actually or maybe a LED trigger. Just set LED's trigger to "this is
> >> display backlight".
> >
> > There is one already:
> >
> > drivers/leds/trigger/ledtrig-backlight.c
> >
> > It adds a LED class device to the fb_notifier_list
> > (drivers/video/fbdev/core/fb_notify.c)
> >
> > using fb_register_client(). The same is used in
> > backlight_device_register (drivers/video/backlight/backlight.c).
> >
> > Actually why do you want to have this driver in the LED subsystem,
> > if it is advertised as "designed for LCD display backlighting"?
> Well this is also advertised as a driver for Smart phone and tablet devices. And having worked with the Android lighting
> solutions this is the preferred subsystem for Android. The Android OS manages the led brightness based on ALS values and in
> turn calls into the driver to control the brightness register through the vendor provided lighting HAL.

Well.. if it can control other LEDs than just backlight, I believe it
can stay in the LED subsystem.

> I am going to look at the backlight source to figure out how to get the same functionality using the backlight subsystem.
> Otherwise I will plug in this driver to the backlight subsystem through the notifier.

The backlight trigger should be ok.

Best regards,
(cesky, pictures)
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