linux-kernel - Re: [linux-sunxi] [PATCH v2 5/5] arm64: allwinner: dts: a64: add LCD-related device nodes for PinePhone

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Message-ID: <20200319161002.kmivhr3ouhoyn4bt@core.my.home>
Date:   Thu, 19 Mar 2020 17:10:02 +0100
From:   Ondřej Jirman <megous@...ous.com>
To:     Icenowy Zheng <icenowy@...c.io>
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Rob Herring <robh+dt@...nel.org>,
        Maxime Ripard <mripard@...nel.org>,
        Chen-Yu Tsai <wens@...e.org>, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...glegroups.com
Subject: Re: [linux-sunxi] [PATCH v2 5/5] arm64: allwinner: dts: a64: add
 LCD-related device nodes for PinePhone

On Thu, Mar 19, 2020 at 10:51:36PM +0800, Icenowy Zheng wrote:
> 在 2020-03-16星期一的 21:35 +0800，Icenowy Zheng写道：
> > PinePhone uses PWM backlight and a XBD599 LCD panel over DSI for
> > display.
> > 
> > Add its device nodes.
> > 
> > Signed-off-by: Icenowy Zheng <icenowy@...c.io>
> > ---
> > No changes in v2.
> > 
> >  .../dts/allwinner/sun50i-a64-pinephone.dtsi   | 37
> > +++++++++++++++++++
> >  1 file changed, 37 insertions(+)
> > 
> > diff --git a/arch/arm64/boot/dts/allwinner/sun50i-a64-pinephone.dtsi
> > b/arch/arm64/boot/dts/allwinner/sun50i-a64-pinephone.dtsi
> > index cefda145c3c9..96d9150423e0 100644
> > --- a/arch/arm64/boot/dts/allwinner/sun50i-a64-pinephone.dtsi
> > +++ b/arch/arm64/boot/dts/allwinner/sun50i-a64-pinephone.dtsi
> > @@ -16,6 +16,15 @@ aliases {
> >  		serial0 = &uart0;
> >  	};
> >  
> > +	backlight: backlight {
> > +		compatible = "pwm-backlight";
> > +		pwms = <&r_pwm 0 50000 PWM_POLARITY_INVERTED>;
> > +		brightness-levels = <0 16 18 20 22 24 26 29 32 35 38 42
> > 46 51 56 62 68 75 83 91 100>;
> 
> Should I drop the 0 here and replace it with 14?

Almost all boards in arm/boot/dts start at 0.

> I have heard community complaining about setting 0 to brightness make
> the screen black.

Level 0 (first value in the list) is special, and turns off the backlight:

123         if (brightness > 0) {
124                 pwm_get_state(pb->pwm, &state);
125                 state.duty_cycle = compute_duty_cycle(pb, brightness);
126                 pwm_apply_state(pb->pwm, &state);
127                 pwm_backlight_power_on(pb);
128         } else {
129                 pwm_backlight_power_off(pb);
130         }

	o.

> (I think in this situation bl_power or blank the DSI panel can still
> totally shut down the backlight).
> 
> > +		default-brightness-level = <15>;
> > +		enable-gpios = <&pio 7 10 GPIO_ACTIVE_HIGH>; /* PH10 */
> > +		power-supply = <&reg_ldo_io0>;
> > +	};
> > +
> >  	chosen {
> >  		stdout-path = "serial0:115200n8";
> >  	};
> > @@ -84,6 +93,30 @@ &dai {
> >  	status = "okay";
> >  };
> >  
> > +&de {
> > +	status = "okay";
> > +};
> > +
> > +&dphy {
> > +	status = "okay";
> > +};
> > +
> > +&dsi {
> > +	vcc-dsi-supply = <&reg_dldo1>;
> > +	#address-cells = <1>;
> > +	#size-cells = <0>;
> > +	status = "okay";
> > +
> > +	panel@0 {
> > +		compatible = "xingbangda,xbd599";
> > +		reg = <0>;
> > +		reset-gpios = <&pio 3 23 GPIO_ACTIVE_LOW>; /* PD23 */
> > +		iovcc-supply = <&reg_dldo2>;
> > +		vcc-supply = <&reg_ldo_io0>;
> > +		backlight = <&backlight>;
> > +	};
> > +};
> > +
> >  &ehci0 {
> >  	status = "okay";
> >  };
> > @@ -188,6 +221,10 @@ &r_pio {
> >  	 */
> >  };
> >  
> > +&r_pwm {
> > +	status = "okay";
> > +};
> > +
> >  &r_rsb {
> >  	status = "okay";
> >  
> > -- 
> > 2.24.1
> > 
>