Re: [PATCH 3/4] backlight: add led-backlight driver

[Jean-Jacques Hiblot]

Pavel

On 05/07/2019 12:08, Pavel Machek wrote:
> Hi!
>
> > > > > Also still relevant is whether the LED device is being correctly
> > > > > modelled if the act of turning on the LED doesn't, in fact, turn the LED
> > > > > on. Is it *really* a correct implementation of an LED device that
> > > > > setting it to LED_FULL using sysfs doesn't cause it to light up?
> > > > What I understood from the discussion between Rob and Tomi is that the
> > > > child-node of the LED controller should be considered a backlight device,
> > > > not a simple LED. I'm not sure if the sysfs interface is still relevant in
> > > > that case. Maybe it should just be disabled by the backlight driver
> > > > (possible with led_sysfs_disable())
> > > led_sysfs_disable() sounds like a sensible change but that's not quite
> > > what I mean.
> > >
> > > It is more a thought experiment to see if the power control *should* be
> > > implemented by the backlight. Consider what happens if we *don't*
> > > enable CONFIG_BACKLIGHT_LED in the kernel: we would still have an LED
> > > device and it would not work correctly.
> > >
> > > In other words I naively expect turning on an LED using the LED API
> > > (any of them, sysfs or kernel) to result in the LED turning on.
> > > Implementing a workaround in the client for what appears to be
> > > something missing in the LED driver strikes me as odd. Why shouldn't
> > > the regulator be managed in the LED driver?
> > I see your point. Indeed having the regulator handled in the LED-core makes
> > sense in a lot of situations
> >
> > I'll think about it.
> For the record, I also believe regulator and enable gpio should be
> handled in the core.

I am working on adding the regulator to the led core.

I don't really want to add a GPIO enable to the core though. If needed 
it can be described as a GPIO-enabled regulator up(/down)stream the 
regular regulator.

JJ


> 									Pavel
> PS please trim down the quoted text.