:: Re: [maemo-leste] Backlight on Droi…
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Autor: Sebastian Reichel
Data:  
A: Pavel Machek
CC: jjhiblot, tomi.valkeinen, Tony Lindgren, Merlijn Wajer, maemo-leste, Ivaylo Dimitrov
Assumpte: Re: [maemo-leste] Backlight on Droid4 -- was Re: Droid 4 in 5.3-rc1, development boards
Hi,

On Mon, Jul 29, 2019 at 10:45:26PM +0200, Pavel Machek wrote:
> Hi!
>
> > On Mon, Jul 29, 2019 at 03:55:23PM +0200, Pavel Machek wrote:
> > > > Oh and the new backlight module comes up blanked right now so it
> > > > needs to be manually enabled via sysfs.
> > >
> > > Or you can enable ledtrig-backlight and apply this.
> > >
> > > (I know, we need better solution).
> >
> > https://lore.kernel.org/lkml/20190717141514.21171-1-jjhiblot@ti.com/
> >
> > The above patchset is the proper solution. It is a backlight
> > driver, which takes the LED driver as input and exposes a
> > proper backlight device. This makes it possible to reference
> > the backlight in DT:
> >
> > ----------------
> > led-node {
> >     blabla;
> > };

> >
> > backlight-node {
> >     blabla;
> >     led = <&led-node>;
> > };

> >
> > panel-node {
> >     backlight = <&backlight-node>;
> > };
> > ----------------

>
> Hmm, I guess I should try to get it to work.
>
> I came up with this, and ... it does not work. If you see
> something obviously wrong, tell me.


DT change looks sensible to me. I did not yet do any test myself.
I'm too busy with converting the omapdrm DSI code to drm_panel.

-- Sebastian

>
> Thanks,
>                                 Pavel

>
> diff --git a/arch/arm/boot/dts/omap4-droid4-xt894.dts b/arch/arm/boot/dts/omap4-droid4-xt894.dts
> index 62af1b8..0195580 100644
> --- a/arch/arm/boot/dts/omap4-droid4-xt894.dts
> +++ b/arch/arm/boot/dts/omap4-droid4-xt894.dts
> @@ -202,12 +202,22 @@
>          };
>      };

>
> +    backlight: backlight {
> +             compatible = "led-backlight";
> +
> +         leds = <&backlight_led>;
> +         brightness-levels = <0 4 8 16 32 64 128 255>;
> +         default-brightness-level = <6>;
> +    };
> +
>      lcd0: display {
>          compatible = "panel-dsi-cm";
>          label = "lcd0";
>          vddi-supply = <&lcd_regulator>;
>          reset-gpios = <&gpio4 5 GPIO_ACTIVE_HIGH>;    /* gpio101 */

>
> +        backlight = <&backlight>;
> +
>          width-mm = <50>;
>          height-mm = <89>;

>
> @@ -417,12 +427,11 @@
>          ramp-up-us = <1024>;
>          ramp-down-us = <8193>;

>
> -        led@0 {
> +        backlight_led: led@0 {
>              reg = <0>;
>              led-sources = <2>;
>              ti,led-mode = <0>;
>              label = ":backlight";
> -            linux,default-trigger = "backlight";
>          };

>
>          led@1 {

>
>
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html