* [PATCH] arm64: dts: qcom: sc7280: Adjust zombie PWM frequency
@ 2023-02-09 2:28 Owen Yang
2023-02-09 19:45 ` Matthias Kaehlcke
0 siblings, 1 reply; 2+ messages in thread
From: Owen Yang @ 2023-02-09 2:28 UTC (permalink / raw)
To: LKML
Cc: Matthias Kaehlcke, Gavin Lee, Doug Anderson, Harvey, Abner Yen,
Stephen Boyd, Bob Moragues, Owen Yang, Andy Gross,
Bjorn Andersson, Konrad Dybcio, Krzysztof Kozlowski, Rob Herring,
devicetree, linux-arm-msm
Tune the PWM to solve screen flashing issue and high frequency noise.
Signed-off-by: Owen Yang <ecs.taipeikernel@gmail.com>
---
arch/arm64/boot/dts/qcom/sc7280-herobrine-zombie.dtsi | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/boot/dts/qcom/sc7280-herobrine-zombie.dtsi b/arch/arm64/boot/dts/qcom/sc7280-herobrine-zombie.dtsi
index 64deaaabac0f..000f64d27ab9 100644
--- a/arch/arm64/boot/dts/qcom/sc7280-herobrine-zombie.dtsi
+++ b/arch/arm64/boot/dts/qcom/sc7280-herobrine-zombie.dtsi
@@ -61,8 +61,8 @@ ap_tp_i2c: &i2c0 {
};
&pm8350c_pwm_backlight {
- /* Set the PWM period to 200 microseconds (5kHz duty cycle) */
- pwms = <&pm8350c_pwm 3 200000>;
+ /* Set the PWM period to 320 microseconds (8kHz duty cycle) */
+ pwms = <&pm8350c_pwm 3 320000>;
};
&pwmleds {
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] arm64: dts: qcom: sc7280: Adjust zombie PWM frequency
2023-02-09 2:28 [PATCH] arm64: dts: qcom: sc7280: Adjust zombie PWM frequency Owen Yang
@ 2023-02-09 19:45 ` Matthias Kaehlcke
0 siblings, 0 replies; 2+ messages in thread
From: Matthias Kaehlcke @ 2023-02-09 19:45 UTC (permalink / raw)
To: Owen Yang
Cc: LKML, Gavin Lee, Doug Anderson, Harvey, Abner Yen, Stephen Boyd,
Bob Moragues, Andy Gross, Bjorn Andersson, Konrad Dybcio,
Krzysztof Kozlowski, Rob Herring, devicetree, linux-arm-msm
On Thu, Feb 09, 2023 at 10:28:16AM +0800, Owen Yang wrote:
> Tune the PWM to solve screen flashing issue and high frequency noise.
>
> Signed-off-by: Owen Yang <ecs.taipeikernel@gmail.com>
> ---
>
> arch/arm64/boot/dts/qcom/sc7280-herobrine-zombie.dtsi | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/qcom/sc7280-herobrine-zombie.dtsi b/arch/arm64/boot/dts/qcom/sc7280-herobrine-zombie.dtsi
> index 64deaaabac0f..000f64d27ab9 100644
> --- a/arch/arm64/boot/dts/qcom/sc7280-herobrine-zombie.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sc7280-herobrine-zombie.dtsi
> @@ -61,8 +61,8 @@ ap_tp_i2c: &i2c0 {
> };
>
> &pm8350c_pwm_backlight {
> - /* Set the PWM period to 200 microseconds (5kHz duty cycle) */
> - pwms = <&pm8350c_pwm 3 200000>;
> + /* Set the PWM period to 320 microseconds (8kHz duty cycle) */
> + pwms = <&pm8350c_pwm 3 320000>;
Is 'duty cycle' really correct here? The unit of the duty cycle is
percent, not kHz and it shouldn't be impacted by this change. I guess
you mean frequency.
And how does this change result in a frequency of 8kHz? Wouldn't it be
3.125 kHz with a peridod of 320us?
^ permalink raw reply [flat|nested] 2+ messages in thread
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2023-02-09 19:45 ` Matthias Kaehlcke
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