Re: [PATCH v2] arm64: dts: qcom: x1e80100-medion-sprchrgd-14-s1: Add PWM backlight

[Konrad Dybcio]

On 10/25/26 8:51 AM, Sérgio Ferreira via B4 Relay wrote:
> From: Sérgio Ferreira <ferreira@xxxxxxxx>
> 
> The eDP panel (CSOT MNE007ZA3-2, IPS LCD) cannot have its brightness
> set over eDP AUX. With no backlight phandle on the panel, panel-edp
> falls back to the DP AUX backlight, which registers dp_aux_backlight
> with a maximum brightness of 0, so brightness control has no effect.
> 
> Brightness is driven by PWM instead. UEFI leaves PM8550 LPG channel 3
> running and the PWM output configured on PM8550 GPIO 8, and drives
> PMC8380_3 GPIO 4 high as the backlight enable:
> 
>   pm8550 gpio8 : out low func1 vin-0 no pull push-pull medium
>   pmc8380_3 gpio4 : out  high normal  vin-1 pull-down push-pull medium
> 
> The panel configuration in the Windows ACPI tables confirmed this.
> (PMIC-controlled PWM, PMIC 1, bank 3, 9-bit, 2 kHz).
> 
> Describe this with a pwm-backlight node: enable pm8550_pwm, add pinctrl
> states for the enable GPIO and for gpio8 func1, and attach the
> backlight to the panel.
> 
> Tested on a Medion SPRCHRGD 14 S1 (X1E78100): brightness control over
> the full range, brightness keys, suspend/resume and restore after
> reboot.
> 
> Assisted-by: LLM
> Signed-off-by: Sérgio Ferreira <ferreira@xxxxxxxx>
> ---

Reviewed-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>

Konrad