linux-kernel - Re: [PATCH] arm64: dts: imx8mm-evk: add pwm1/backlight support

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Message-ID: <20220413124030.GB4713@tom-ThinkPad-T14s-Gen-2i>
Date:   Wed, 13 Apr 2022 14:40:30 +0200
From:   Tommaso Merciai <tommaso.merciai@...rulasolutions.com>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     linux-amarula@...rulasolutions.com,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Joakim Zhang <qiangqing.zhang@....com>,
        Tim Harvey <tharvey@...eworks.com>,
        Richard Zhu <hongxing.zhu@....com>, Li Jun <jun.li@....com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: dts: imx8mm-evk: add pwm1/backlight support

On Wed, Apr 13, 2022 at 02:27:00PM +0200, Krzysztof Kozlowski wrote:
> On 13/04/2022 13:58, Tommaso Merciai wrote:
> >>> +	backlight: backlight {
> >>> +		status = "disabled";
> >>
> >> Why disabled?
> >>
> >>> +		compatible = "pwm-backlight";
> >>> +		pwms = <&pwm1 0 5000000>;
> >>> +		brightness-levels = <0 255>;
> >>> +		num-interpolated-steps = <255>;
> >>> +		default-brightness-level = <250>;
> >>> +	};
> >>> +
> >>>  	ir-receiver {
> >>>  		compatible = "gpio-ir-receiver";
> >>>  		gpios = <&gpio1 13 GPIO_ACTIVE_LOW>;
> >>> @@ -395,6 +404,12 @@ &wdog1 {
> >>>  	status = "okay";
> >>>  };
> >>>  
> >>> +&pwm1 {
> >>> +	pinctrl-names = "default";
> >>> +	pinctrl-0 = <&pinctrl_backlight>;
> >>> +	status = "disabled";
> >>
> >> Same here.
> >>
> >>
> >> Best regards,
> >> Krzysztof
> > 
> > Hi Krzysztof,
> > I think is better to keep disable into .dtsi and enable it at .dts
> > level.
> > What do you think about?
> 
> Why better? This is already board DTSI, not a SoC DTSI. All boards using
> it are supposed to have it available, aren't they?
> 
> Usually nodes should be disabled in a DTSI if they need some resources
> not available in that DTSI. For example if they need some supply. It's
> not the case here, right?

Hi Krzysztof,
Yes, right I check both schematics (DSI_BL_PWM). We can set PWM enable.
I'll update status in v2.

> 
> 
> Best regards,
> Krzysztof

Regards,
Tommaso

-- 
Tommaso Merciai
Embedded Linux Engineer
tommaso.merciai@...rulasolutions.com
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