Re: [PATCH 3/3] backlight: lp8864: Convert from LED to backlight class driver

[Daniel Thompson <daniel@riscstar.com>]

On Tue, Jun 23, 2026 at 11:59:16AM +0000, Sverdlin, Alexander wrote:
> Hi Daniel,
> 
> On Tue, 2026-06-23 at 12:41 +0100, Daniel Thompson wrote:
> > > The mechanism we have regarding hot plugging currently is just I2C bridge,
> > > which de-registers and registers the bridged bus. So no additional drivers
> > > are required, as long as I2C devices are self-contained and not glued with
> > > platform devices.
> > > 
> > > So bottom line is, I'd prefer to just add the backlight interface to the
> > > existing driver, no matter where it would live in the future.
> > 
> > Is there any reasion that LP8864/LP8866 is unique in appearing on a 
> > hotplugged I2C bus? In other words if support for dynamism is added
> > specifically to leds-lp8864.c rather than in led_bl.c then what will stop
> > the same dynamic tricks from being adde to other LED drivers?
> 
> LP8864 is not special in this regard, not different from adp8860_bl.c,
> adp8870_bl.c or lm3639_bl.c, which would work in my application.

The most recent of these drivers adopted LED support in 2012 whilst
led_bl.c was introduced in 2020.


> So I just wanted to add currently missing backlight_device_register() to
> LP8864, but there were no such dual-API drivers under drivers/leds/ that's
> wht I started with moving LP8864 driver into drivers/video/backlight/.
> 
> led_bl.c however could only be hot-pluggable either if one actively
> creates/destroys platform device somewhere in the code programmatically
> or uses DT overlays.
> 
> Just adding backlight API to LP8864 would be much more idiomatic, I'd
> say.

Maybe.

I think I might consider the drivers above to be historical anomalies
rather than idiomatic examples.


Daniel.