Hi,
On Wed, May 24, 2017 at 08:13:20PM +0800, Icenowy Zheng wrote:
> The 40-pin LCD connector on Lichee Pi Zero has backlight pins, which is
> controlled by the PWM0 controller of the V3s SoC, and the controlling
> part is on the board.
>
> Add the PWM and backlight device nodes in the device tree file, but
> leave them disabled, as they can only be useful when the LCD is
> attached. The LCD device tree overlay files can enable these controllers
> and make use of them.
>
> Signed-off-by: Icenowy Zheng <icenowy@xxxxxxx>
> ---
> arch/arm/boot/dts/sun8i-v3s-licheepi-zero.dts | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/arch/arm/boot/dts/sun8i-v3s-licheepi-zero.dts b/arch/arm/boot/dts/sun8i-v3s-licheepi-zero.dts
> index 387fc2aa546d..e0721bf725d1 100644
> --- a/arch/arm/boot/dts/sun8i-v3s-licheepi-zero.dts
> +++ b/arch/arm/boot/dts/sun8i-v3s-licheepi-zero.dts
> @@ -52,6 +52,14 @@
> serial0 = &uart0;
> };
>
> + backlight: backlight {
> + compatible = "pwm-backlight";
> + pwms = <&pwm 0 50000 0>;
> + brightness-levels = <0 10 20 30 40 50 60 70 80 90 100>;
This is unlikely, the perceived brightness by the human eye is not
linear, and is actually much closer to a logarithmic function, which
means you should have use an exponential function here in order to
appear that your brightness increase is linear.
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
Attachment:
signature.asc
Description: PGP signature
