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Subject: Re: [PATCH 1/2] arm64: dts: meson: add spdif out to khadas-vim
To:     Artem Lapkin <email2tema@gmail.com>
Cc:     jbrunet@baylibre.com, linux-arm-kernel@lists.infradead.org,
        linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org,
        christianshewitt@gmail.com, art@khadas.com, nick@khadas.com,
        gouwa@khadas.com
References: <20210810041630.3673406-1-art@khadas.com>
From:   Neil Armstrong <narmstrong@baylibre.com>
Organization: Baylibre
Message-ID: <7dbba936-e8ab-4d47-1af8-0d3d1adb8c30@baylibre.com>
Date:   Tue, 10 Aug 2021 09:55:19 +0200
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Hi,

On 10/08/2021 06:16, Artem Lapkin wrote:
> Add spdif output audio support to khadas-vim
> 
> Signed-off-by: Artem Lapkin <art@khadas.com>
> ---
>  .../dts/amlogic/meson-gxl-s905x-khadas-vim.dts  | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/amlogic/meson-gxl-s905x-khadas-vim.dts b/arch/arm64/boot/dts/amlogic/meson-gxl-s905x-khadas-vim.dts
> index 60feac0179c0..01f13822a616 100644
> --- a/arch/arm64/boot/dts/amlogic/meson-gxl-s905x-khadas-vim.dts
> +++ b/arch/arm64/boot/dts/amlogic/meson-gxl-s905x-khadas-vim.dts
> @@ -64,6 +64,13 @@ hdmi_connector_in: endpoint {
>  		};
>  	};
>  
> +	spdif_dit: audio-codec-0 {
> +		#sound-dai-cells = <0>;
> +		compatible = "linux,spdif-dit";
> +		status = "okay";
> +		sound-name-prefix = "DIT";
> +	};
> +
>  	sound {
>  		compatible = "amlogic,gx-sound-card";
>  		model = "KHADAS-VIM";
> @@ -97,11 +104,21 @@ codec-0 {
>  				sound-dai = <&hdmi_tx>;
>  			};
>  		};
> +
> +		dai-link-3 {
> +			sound-dai = <&aiu AIU_CPU CPU_SPDIF_ENCODER>;
> +
> +			codec-0 {
> +				sound-dai = <&spdif_dit>;
> +			};
> +		};
>  	};
>  };
>  
>  &aiu {
>  	status = "okay";
> +	pinctrl-0 = <&spdif_out_h_pins>;
> +	pinctrl-names = "default";
>  };
>  
>  &cec_AO {
> 

AFAIK the board doesn't have a physical SPDIF output, but one of the 40pin header can output SPDIF, right ?

In this case, following the other boards mainline definitions, we do not enable any function by default
for pins on the 40pin (or other programmable) headers.

There is still ongoing discussions on how to handle that on a more generic level, but you should write a bunch
of DT overlays for the VIM boards to enable optional functions like SPDIF and store then in a public git
tree for everybody to use (like armbian or LibreELEC for example) from the U-Boot stage.

Neil