From: Matthias Kaehlcke <mka@chromium.org>
To: Owen Yang <ecs.taipeikernel@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Gavin Lee <gavin.lee@ecs.com.tw>,
Doug Anderson <dianders@chromium.org>, Harvey <hunge@google.com>,
Abner Yen <abner.yen@ecs.com.tw>,
Stephen Boyd <swboyd@chromium.org>,
Bob Moragues <moragues@google.com>,
Andy Gross <agross@kernel.org>,
Bjorn Andersson <andersson@kernel.org>,
Konrad Dybcio <konrad.dybcio@linaro.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH] arm64: dts: qcom: sc7280: Adjust zombie PWM frequency
Date: Thu, 9 Feb 2023 19:45:31 +0000 [thread overview]
Message-ID: <Y+VNW3ikQVgXK4VV@google.com> (raw)
In-Reply-To: <20230209102807.1.I3e1463cd0fb66311a269f2698d0767a2acfaac3f@changeid>
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?
prev parent reply other threads:[~2023-02-09 19:45 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-09 2:28 [PATCH] arm64: dts: qcom: sc7280: Adjust zombie PWM frequency Owen Yang
2023-02-09 19:45 ` Matthias Kaehlcke [this message]
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