Re: [PATCH] arm64: dts: qcom: Add backlight support for eDP panel

[Yongxing Mou]

On 10/28/2025 5:08 PM, Konrad Dybcio wrote:
> On 10/28/25 8:04 AM, Yongxing Mou wrote:
> > Previously, the eDP panel backlight was enabled via UEFI. Added backlight
> > control node in kernel DTS due to some meta may not enable the backlight.
> >
> > Aligned with other x1e80100-based platforms: the PWM signal is controlled
> > by PMK8550, and the backlight enable signal is handled by PMC8380.
> >
> > Signed-off-by: Yongxing Mou <yongxing.mou@xxxxxxxxxxxxxxxx>
> > ---
>
> The subject must say "hamoa-iot-evk:"
Thanks and got it , will fix it in next version.>> 
arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts | 55 
++++++++++++++++++++++++++++++
> >   1 file changed, 55 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts b/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts
> > index 36dd6599402b4650b7f8ad2c0cd22212116a25fe..fda1b3a3c7673be74832c27849231cba4bc1f25f 100644
> > --- a/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts
> > +++ b/arch/arm64/boot/dts/qcom/hamoa-iot-evk.dts
> > @@ -17,6 +17,16 @@ aliases {
> >   		serial1 = &uart14;
> >   	};
> >   
> > +	backlight: backlight {
> > +		compatible = "pwm-backlight";
> > +		pwms = <&pmk8550_pwm 0 5000000>;
>
> Try adjusting the backlight value.. you'll find some funny behavior
> near the max level.. which reminds me I should send some fixes for
> some laptop DTs
 I tried sliding the backlight between the maximum and minimum values. 
It seems that at a certain sliding speed, when approaching the maximum 
value, there is some brightness flickering. Is this the phenomenon 
you’re referring to?> [...]
> > +	vreg_edp_bl: regulator-edp-bl {
> > +		compatible = "regulator-fixed";
> > +
> > +		regulator-name = "VBL9";
> > +		regulator-min-microvolt = <3600000>;
> > +		regulator-max-microvolt = <3600000>;
> > +
> > +		gpio = <&pmc8380_3_gpios 10 GPIO_ACTIVE_HIGH>;
> > +		enable-active-high;
> > +
> > +		pinctrl-names = "default";
> > +		pinctrl-0 = <&edp_bl_reg_en>;
>
> property-n
> property-names
>
> in this order, please
>
> KonradThanks and got it ,will fix it in next version.