Am 08.08.2020 um 11:56 schrieb David Shah dave@ds0.me:

Increase PWM frequency to 8300Hz as LM3699 datasheet recommends a frequency between 2kHz and 100kHz.

Yes, that is right!

The 83 Hz (12000000) is probably from (too) simply copying from the (old) display backlight which was limited to ca. 200 Hz.

What I am not sure is if all mainboard variants have the lm3699 or if we must patch specific variants.

BR and thanks, Nikolaus

Signed-off-by: David Shah dave@ds0.me

arch/arm/boot/dts/pyra-mainboard-common.dtsi | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/pyra-mainboard-common.dtsi b/arch/arm/boot/dts/pyra-mainboard-common.dtsi index 67aca9b084de..91691c4f25de 100644 --- a/arch/arm/boot/dts/pyra-mainboard-common.dtsi +++ b/arch/arm/boot/dts/pyra-mainboard-common.dtsi @@ -88,7 +88,7 @@ modem_en: modem {

keyboard-backlight { compatible = "pwm-backlight";

• pwms = <&pwm8 0 12000000 0>;
  

• pwms = <&pwm8 0 120000 0>; // 8300Hz
  

  pwm-names = "keyboard"; brightness-levels = <0 1 2 5 10 20 40 60 100>; default-brightness-level = <5>; /* 20% */

-- 2.27.0

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