Re: [PATCH/RFC 12/12] arm64: dts: renesas: Add EK874 board with idk-2121wr display support

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Fabrizio,

On Mon, Aug 05, 2019 at 09:37:29AM +0000, Fabrizio Castro wrote:
> On 02 August 2019 09:34 Laurent Pinchart wrote:
> > On Fri, Aug 02, 2019 at 08:34:09AM +0100, Fabrizio Castro wrote:
> > > The EK874 is advertised as compatible with panel IDK-2121WR from
> > > Advantech, however the panel isn't sold alongside the board.
> > > A new dts, adding everything that's required to get the panel to
> > > to work with the EK874, is the most convenient way to support the
> > > EK874 when it's connected to the IDK-2121WR.
> > >
> > > Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
> > > ---
> > >  arch/arm64/boot/dts/renesas/Makefile               |   3 +-
> > >  .../boot/dts/renesas/r8a774c0-ek874-idk-2121wr.dts | 112 +++++++++++++++++++++
> > >  2 files changed, 114 insertions(+), 1 deletion(-)
> > >  create mode 100644 arch/arm64/boot/dts/renesas/r8a774c0-ek874-idk-2121wr.dts
> > >
> > > diff --git a/arch/arm64/boot/dts/renesas/Makefile b/arch/arm64/boot/dts/renesas/Makefile
> > > index 42b74c2..ce48478 100644
> > > --- a/arch/arm64/boot/dts/renesas/Makefile
> > > +++ b/arch/arm64/boot/dts/renesas/Makefile
> > > @@ -1,7 +1,8 @@
> > >  # SPDX-License-Identifier: GPL-2.0
> > >  dtb-$(CONFIG_ARCH_R8A774A1) += r8a774a1-hihope-rzg2m.dtb
> > >  dtb-$(CONFIG_ARCH_R8A774A1) += r8a774a1-hihope-rzg2m-ex.dtb
> > > -dtb-$(CONFIG_ARCH_R8A774C0) += r8a774c0-cat874.dtb r8a774c0-ek874.dtb
> > > +dtb-$(CONFIG_ARCH_R8A774C0) += r8a774c0-cat874.dtb r8a774c0-ek874.dtb \
> > > +			       r8a774c0-ek874-idk-2121wr.dtb
> > >  dtb-$(CONFIG_ARCH_R8A7795) += r8a7795-salvator-x.dtb r8a7795-h3ulcb.dtb
> > >  dtb-$(CONFIG_ARCH_R8A7795) += r8a7795-h3ulcb-kf.dtb
> > >  dtb-$(CONFIG_ARCH_R8A7795) += r8a7795-salvator-xs.dtb
> > > diff --git a/arch/arm64/boot/dts/renesas/r8a774c0-ek874-idk-2121wr.dts b/arch/arm64/boot/dts/renesas/r8a774c0-ek874-idk-
> > 2121wr.dts
> > > new file mode 100644
> > > index 0000000..d989998
> > > --- /dev/null
> > > +++ b/arch/arm64/boot/dts/renesas/r8a774c0-ek874-idk-2121wr.dts
> > > @@ -0,0 +1,112 @@
> > > +// SPDX-License-Identifier: GPL-2.0
> > > +/*
> > > + * Device Tree Source for the Silicon Linux RZ/G2E evaluation kit (EK874),
> > > + * connected to an Advantech IDK-2121WR 21.5" LVDS panel
> > > + *
> > > + * Copyright (C) 2019 Renesas Electronics Corp.
> > > + */
> > > +
> > > +#include "r8a774c0-ek874.dts"
> > > +
> > > +/ {
> > > +	backlight: backlight {
> > > +		compatible = "pwm-backlight";
> > > +		pwms = <&pwm5 0 50000>;
> > > +
> > > +		brightness-levels = <0 4 8 16 32 64 128 255>;
> > > +		default-brightness-level = <6>;
> > > +
> > > +		power-supply = <&reg_12p0v>;
> > > +		enable-gpios = <&gpio6 12 GPIO_ACTIVE_HIGH>;
> > > +	};
> > > +
> > > +	panel-lvds {
> > > +		compatible = "advantech,idk-2121wr", "panel-lvds";
> > > +
> > > +		width-mm = <476>;
> > > +		height-mm = <268>;
> > > +
> > > +		data-mapping = "vesa-24";
> > > +
> > > +		panel-timing {
> > > +			clock-frequency = <148500000>;
> > > +			hactive = <1920>;
> > > +			vactive = <1080>;
> > > +			hsync-len = <44>;
> > > +			hfront-porch = <88>;
> > > +			hback-porch = <148>;
> > > +			vfront-porch = <4>;
> > > +			vback-porch = <36>;
> > > +			vsync-len = <5>;
> > > +		};
> > > +
> > > +		ports {
> > > +			#address-cells = <1>;
> > > +			#size-cells = <0>;
> > > +
> > > +			port@0 {
> > > +				reg = <0>;
> > > +				lvds0_panel_in: endpoint {
> > > +					remote-endpoint = <&lvds0_out>;
> > > +				};
> > > +			};
> > > +
> > > +			port@1 {
> > > +				reg = <1>;
> > > +				lvds1_panel_in: endpoint {
> > > +					remote-endpoint = <&lvds1_out>;
> > > +				};
> > > +			};
> > > +		};
> > > +	};
> > > +};
> > > +
> > > +&gpio0 {
> > > +	lvds-connector-en-gpio{
> > > +		gpio-hog;
> > > +		gpios = <17 GPIO_ACTIVE_HIGH>;
> > > +		output-low;
> > > +		line-name = "lvds-connector-en-gpio";
> > > +	};
> > 
> > Any chance to specify this as the panel's enable signal in the panel DT
> > node ?
> 
> I am not too sure, as this is not exactly an enable signal. When GP0_17 is low
> then LVDS[01] are connected to the LVDS connector, when GP0_17 is high
> then LVDS[01] are connected to the LT8918L.
> Perhaps we should leave this fixed to low to avoid confusion?

The line-name was confusing me. A GPIO hog is thus indeed the best
option. A comment that explains what the signal is for could help.

> > > +};
> > > +
> > > +&lvds0 {
> > > +	renesas,swap-data;
> > 
> > Let's discuss this property in reply to the DT bindings patch.
> > 
> > > +
> > > +	ports {
> > > +		port@1 {
> > > +			lvds0_out: endpoint {
> > > +				remote-endpoint = <&lvds0_panel_in>;
> > > +			};
> > > +		};
> > > +	};
> > > +};
> > > +
> > > +&lvds1 {
> > > +	status = "okay";
> > > +
> > > +	clocks = <&cpg CPG_MOD 727>, <&x13_clk>, <&extal_clk>;
> > > +	clock-names = "fck", "dclkin.0", "extal";
> > > +
> > > +	ports {
> > > +		port@1 {
> > > +			lvds1_out: endpoint {
> > > +				remote-endpoint = <&lvds1_panel_in>;
> > > +			};
> > > +		};
> > > +	};
> > > +};
> > > +
> > > +&pfc {
> > > +	pwm5_pins: pwm5 {
> > > +		groups = "pwm5_a";
> > > +		function = "pwm5";
> > > +	};
> > > +};
> > > +
> > > +&pwm5 {
> > > +	pinctrl-0 = <&pwm5_pins>;
> > > +	pinctrl-names = "default";
> > > +
> > > +	status = "okay";
> > > +};
> > 
> > I haven't reviewed pinouts in detail, but the patch otherwise looks sane
> > to me. Another candidate for DT overlays though ;-)

-- 
Regards,

Laurent Pinchart