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Date: Mon, 15 Apr 2024 19:35:20 +0300
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Kieran Bingham <kieran.bingham@ideasonboard.com>
Cc: Christopher Obbard <chris.obbard@collabora.com>,
	linux-kernel@vger.kernel.org,
	Daniel Scally <dan.scally@ideasonboard.com>, kernel@collabora.com,
	Conor Dooley <conor+dt@kernel.org>,
	Fabio Estevam <festevam@gmail.com>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Pengutronix Kernel Team <kernel@pengutronix.de>,
	Rob Herring <robh@kernel.org>,
	Sascha Hauer <s.hauer@pengutronix.de>,
	Shawn Guo <shawnguo@kernel.org>, devicetree@vger.kernel.org,
	imx@lists.linux.dev, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v1 1/1] arm64: dts: imx8mp-debix-model-a: Add HDMI output
 support
Message-ID: <20240415163520.GA22954@pendragon.ideasonboard.com>
References: <20240415114135.25473-1-chris.obbard@collabora.com>
 <20240415114135.25473-2-chris.obbard@collabora.com>
 <171319369093.2333277.9109576229211275635@ping.linuxembedded.co.uk>
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In-Reply-To: <171319369093.2333277.9109576229211275635@ping.linuxembedded.co.uk>

On Mon, Apr 15, 2024 at 04:08:10PM +0100, Kieran Bingham wrote:
> Hi Chris,
> 
> 
> Quoting Christopher Obbard (2024-04-15 12:41:27)
> > Enable the HDMI output on the Debix Model A SBC, using the HDMI encoder
> > present in the i.MX8MP SoC.
> 
> Aha, you beat me to it. I have a commit locally (Dated 2022-09-06) but
> not sent because I didn't realise the HDMI support finally got upstream
> \o/
> 
> > Signed-off-by: Christopher Obbard <chris.obbard@collabora.com>
> > ---
> > 
> >  .../dts/freescale/imx8mp-debix-model-a.dts    | 47 +++++++++++++++++++
> >  1 file changed, 47 insertions(+)
> > 
> > diff --git a/arch/arm64/boot/dts/freescale/imx8mp-debix-model-a.dts b/arch/arm64/boot/dts/freescale/imx8mp-debix-model-a.dts
> > index 2c19766ebf09..29529c2ecac9 100644
> > --- a/arch/arm64/boot/dts/freescale/imx8mp-debix-model-a.dts
> > +++ b/arch/arm64/boot/dts/freescale/imx8mp-debix-model-a.dts
> > @@ -20,6 +20,18 @@ chosen {
> >                 stdout-path = &uart2;
> >         };
> >  
> > +       hdmi-connector {
> > +               compatible = "hdmi-connector";
> > +               label = "hdmi";
> > +               type = "a";
> > +
> > +               port {
> > +                       hdmi_connector_in: endpoint {
> > +                               remote-endpoint = <&hdmi_tx_out>;
> > +                       };
> > +               };
> > +       };
> > +
> 
> Interesting. My patch missed this. But it looks correct.
> 
> >         leds {
> >                 compatible = "gpio-leds";
> >                 pinctrl-names = "default";
> > @@ -94,6 +106,28 @@ ethphy0: ethernet-phy@0 { /* RTL8211E */
> >         };
> >  };
> >  
> > +&hdmi_pvi {
> > +       status = "okay";
> > +};
> > +
> > +&hdmi_tx {
> > +       pinctrl-names = "default";
> > +       pinctrl-0 = <&pinctrl_hdmi>;
> > +       status = "okay";
> > +
> > +       ports {
> > +               port@1 {
> > +                       hdmi_tx_out: endpoint {
> > +                               remote-endpoint = <&hdmi_connector_in>;
> > +                       };
> > +               };
> > +       };
> > +};
> > +
> > +&hdmi_tx_phy {
> > +       status = "okay";
> > +};
> > +
> >  &i2c1 {
> >         clock-frequency = <400000>;
> >         pinctrl-names = "default";
> > @@ -241,6 +275,10 @@ &i2c6 {
> >         status = "okay";
> >  };
> >  
> > +&lcdif3 {
> > +       status = "okay";
> > +};
> > +
> 
> Except for the addition of the connector, the above matches my patch to
> here.
> 
> >  &snvs_pwrkey {
> >         status = "okay";
> >  };
> 
> But in my patch I have the following hunk here: (I haven't checked to
> see if this still applies on mainline, so take with a pinch of salt if
> it's not there!)
> 
> 
>  &iomuxc {
>  	pinctrl-names = "default";
> -	pinctrl-0 = <&pinctrl_hog>;
> -
> -	pinctrl_hog: hoggrp {
> -		fsl,pins = <
> -			MX8MP_IOMUXC_HDMI_DDC_SCL__HDMIMIX_HDMI_SCL					0x400001c3
> -			MX8MP_IOMUXC_HDMI_DDC_SDA__HDMIMIX_HDMI_SDA					0x400001c3
> -			MX8MP_IOMUXC_HDMI_HPD__HDMIMIX_HDMI_HPD						0x40000019
> -			MX8MP_IOMUXC_HDMI_CEC__HDMIMIX_HDMI_CEC						0x40000019
> -		>;
> -	};
> 
>  	pinctrl_eqos: eqosgrp {
>  		fsl,pins = <
>  			MX8MP_IOMUXC_ENET_MDC__ENET_QOS_MDC							0x3
>  			MX8MP_IOMUXC_ENET_MDIO__ENET_QOS_MDIO						0x3
> 
> 
> > @@ -358,6 +396,15 @@ MX8MP_IOMUXC_NAND_READY_B__GPIO3_IO16                              0x19
> >                 >;
> >         };
> >  
> > +       pinctrl_hdmi: hdmigrp {
> > +               fsl,pins = <
> > +                       MX8MP_IOMUXC_HDMI_DDC_SCL__HDMIMIX_HDMI_SCL                     0x400001c3
> > +                       MX8MP_IOMUXC_HDMI_DDC_SDA__HDMIMIX_HDMI_SDA                     0x400001c3
> > +                       MX8MP_IOMUXC_HDMI_HPD__HDMIMIX_HDMI_HPD                         0x40000019
> > +                       MX8MP_IOMUXC_HDMI_CEC__HDMIMIX_HDMI_CEC                         0x40000019
> > +               >;
> > +       };
> > +
> 
> And my addition here is :
> 
> 
> +	pinctrl_hdmi: hdmigrp {
> +		fsl,pins = <
> +			MX8MP_IOMUXC_HDMI_DDC_SCL__HDMIMIX_HDMI_SCL	0x1c3
> +			MX8MP_IOMUXC_HDMI_DDC_SDA__HDMIMIX_HDMI_SDA	0x1c3
> +			MX8MP_IOMUXC_HDMI_HPD__HDMIMIX_HDMI_HPD		0x19
> +			MX8MP_IOMUXC_HDMI_CEC__HDMIMIX_HDMI_CEC		0x19
> +		>;
> +	};
> +
> 
> 
> I haven't looked into what the 0x40000000 does yet, but just
> highlighting the difference from the version I've been using to make use
> of HDMI so far.
> 
> Does anyone else know the impact here? Otherwise I'll try to find time
> to check this later. (For some undefined term of later...)

In drivers/pinctrl/freescale/pinctrl-imx.c,

#define IMX_NO_PAD_CTL  0x80000000      /* no pin config need */
#define IMX_PAD_SION 0x40000000         /* set SION */

The SION (Software Input ON) bit forces the input path active for the
pin. This can be used, for instance, to capture through GPIO the value
of a pin driven by a module. I'm not sure that's needed here.

> >         pinctrl_i2c1: i2c1grp {
> >                 fsl,pins = <
> >                         MX8MP_IOMUXC_I2C1_SCL__I2C1_SCL                                 0x400001c2

-- 
Regards,

Laurent Pinchart