[PATCH v2 1/2] arm64: dts: rockchip: use codec as clock master on px30-ringneck-haikou

[quentin.schulz at theobroma-systems.com]

Hi Jakob,

On 8/23/23 3:16 PM, Jakob Unterwurzacher <jakobunt at gmail.com> wrote:
> From: Ermin Sunj <ermin.sunj at theobroma-systems.com>
> 
> If the codec is not the clock master, the MCLK needs to be
> synchronous to both I2S_SCL ans I2S_LRCLK. We do not have that
> on Haikou, causing distorted audio.
> 
> Before:
> 
>   Running an audio test script on Ringneck, 1kHz
>   output sine wave is not stable and shows distortion.
> 
> After:
> 
>   10h audio test script loop failed only one time.
>   That is 0.00014% failure rate.
> 
> Signed-off-by: Ermin Sunj <ermin.sunj at theobroma-systems.com>
> Signed-off-by: Jakob Unterwurzacher <jakob.unterwurzacher at theobroma-systems.com>
> ---
>   arch/arm64/boot/dts/rockchip/px30-ringneck-haikou.dts | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/boot/dts/rockchip/px30-ringneck-haikou.dts b/arch/arm64/boot/dts/rockchip/px30-ringneck-haikou.dts
> index 3a447d03e2a8..dafeef0c2dab 100644
> --- a/arch/arm64/boot/dts/rockchip/px30-ringneck-haikou.dts
> +++ b/arch/arm64/boot/dts/rockchip/px30-ringneck-haikou.dts
> @@ -68,8 +68,10 @@ i2s0-sound {
>   		simple-audio-card,format = "i2s";
>   		simple-audio-card,name = "Haikou,I2S-codec";
>   		simple-audio-card,mclk-fs = <512>;
> +		simple-audio-card,frame-master = <&sgtl5000_codec>;
> +		simple-audio-card,bitclock-master = <&sgtl5000_codec>;
>   
> -		simple-audio-card,codec {
> +		sgtl5000_codec: simple-audio-card,codec {
>   			clocks = <&sgtl5000_clk>;
>   			sound-dai = <&sgtl5000>;
>   		};
> 

It isn't actually shown in the diff here but we now have two different bitclock and frame masters, specified differently, c.f.:

https://gitlab.com/linux-kernel/linux/-/blob/master/arch/arm64/boot/dts/rockchip/px30-ringneck-haikou.dts?ref_type=heads#L78-L79

So I very much assume we should also delete those two lines in the simple-audio-card,cpu node?

Cheers,
Quentin