linux-kernel - Re: [PATCH v2 2/3] arm64: dts: rk3399: i2s: switch BCLK to GPIO

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Date:   Thu, 16 Jun 2022 13:39:58 -0700
From:   Brian Norris <briannorris@...omium.org>
To:     Judy Hsiao <judyhsiao@...omium.org>
Cc:     Heiko Stuebner <heiko@...ech.de>,
        Liam Girdwood <lgirdwood@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Chen-Yu Tsai <wenst@...omium.org>, alsa-devel@...a-project.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] arm64: dts: rk3399: i2s: switch BCLK to GPIO

Hi,

On Thu, Jun 16, 2022 at 03:58:35PM +0000, Judy Hsiao wrote:
> We discoverd that the state of BCLK on, LRCLK off and SD_MODE on
> may cause the speaker melting issue. Removing LRCLK while BCLK
> is present can cause unexpected output behavior including a large
> DC output voltage as described in the Max98357a datasheet.
> 
> In order to:
>   1. prevent BCLK from turning on by other component.
>   2. keep BCLK and LRCLK being present at the same time
> 
> This patch adjusts the device tree to allow BCLK to switch
> to GPIO func before LRCLK output, and switch back during
> LRCLK is output.
> 
> Signed-off-by: Judy Hsiao <judyhsiao@...omium.org>


> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> @@ -1662,9 +1662,10 @@ i2s0: i2s@...80000 {
>  		dma-names = "tx", "rx";
>  		clock-names = "i2s_clk", "i2s_hclk";
>  		clocks = <&cru SCLK_I2S0_8CH>, <&cru HCLK_I2S0_8CH>;
> -		pinctrl-names = "default";
> +		pinctrl-names = "bclk_on", "bclk_off";
>  		pinctrl-0 = <&i2s0_8ch_bus>;
>  		power-domains = <&power RK3399_PD_SDIOAUDIO>;
> +		pinctrl-1 = <&i2s0_8ch_bus_bclk_off>;

It seems like 'pinctrl-1' may make sense after pinctrl-0, not here.
Perhaps you're interacting with my RFC PATCH that removes this
'power-domains' property?

https://lore.kernel.org/linux-rockchip/20220613183556.RFC.1.I9ca71105e505f024d53b7e0ba4462230813ebb8d@changeid/

But that most likely isn't landing upstream as-is.

Otherwise, this patch looks good to me:

Reviewed-by: Brian Norris <briannorris@...omium.org>

>  		#sound-dai-cells = <0>;
>  		status = "disabled";
>  	};