The board integrates an on-board mux to route shared signals to either
CAN2 or PDM (MICFIL). The mux is controlled by a GPIO.

Add a pinctrl-based multiplexer node to describe this routing and ensure
proper probe ordering of the dependent devices.

Previously, MICFIL operation implicitly depended on the default level of
PCA6416 GPIO3. After adding the pinctrl-multiplexer, make the dependency
explicit.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
change in v3
- none
change in v2
- update commit message to show why need update PDM MICIFL.
---
 arch/arm64/boot/dts/freescale/imx8mp-evk.dts | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/freescale/imx8mp-evk.dts b/arch/arm64/boot/dts/freescale/imx8mp-evk.dts
index b256be710ea1281465f5cecc7a3b979f2c068e43..1341ee27239fd41a26117adc9023524ce50420a7 100644
--- a/arch/arm64/boot/dts/freescale/imx8mp-evk.dts
+++ b/arch/arm64/boot/dts/freescale/imx8mp-evk.dts
@@ -50,6 +50,25 @@ status {
 		};
 	};
 
+	can_mux: mux-controller-0 {
+		compatible = "gpio-mux";
+		#mux-control-cells = <0>;
+		#mux-state-cells = <1>;
+		mux-gpios = <&pca6416 3 GPIO_ACTIVE_HIGH>;
+	};
+
+	can_mux_pinctrl: pinctrl-gpiomux {
+		compatible = "pinctrl-multiplexer";
+
+		can_fun: can-grp {
+			mux-states = <&can_mux 1>;
+		};
+
+		pdm_fun: pdm-grp {
+			mux-states = <&can_mux 0>;
+		};
+	};
+
 	memory@40000000 {
 		device_type = "memory";
 		reg = <0x0 0x40000000 0 0xc0000000>,
@@ -446,7 +465,7 @@ &flexcan1 {
 
 &flexcan2 {
 	pinctrl-names = "default";
-	pinctrl-0 = <&pinctrl_flexcan2>;
+	pinctrl-0 = <&pinctrl_flexcan2>, <&can_fun>;
 	phys = <&flexcan_phy 1>;
 	status = "disabled";/* can2 pin conflict with pdm */
 };
@@ -712,7 +731,7 @@ &lcdif3 {
 &micfil {
 	#sound-dai-cells = <0>;
 	pinctrl-names = "default";
-	pinctrl-0 = <&pinctrl_pdm>;
+	pinctrl-0 = <&pinctrl_pdm>, <&pdm_fun>;
 	assigned-clocks = <&clk IMX8MP_CLK_PDM>;
 	assigned-clock-parents = <&clk IMX8MP_AUDIO_PLL1_OUT>;
 	assigned-clock-rates = <196608000>;

-- 
2.43.0

On 3/11/26 8:08 PM, Frank Li wrote:
> The board integrates an on-board mux to route shared signals to either
> CAN2 or PDM (MICFIL). The mux is controlled by a GPIO.
> 
> Add a pinctrl-based multiplexer node to describe this routing and ensure
> proper probe ordering of the dependent devices.
> 
> Previously, MICFIL operation implicitly depended on the default level of
> PCA6416 GPIO3. After adding the pinctrl-multiplexer, make the dependency
> explicit.
> 
> Signed-off-by: Frank Li <Frank.Li@nxp.com>

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

I really like this new abstraction.

> +	can_mux_pinctrl: pinctrl-gpiomux {
> +		compatible = "pinctrl-multiplexer";
> +
> +		can_fun: can-grp {
> +			mux-states = <&can_mux 1>;
> +		};
> +
> +		pdm_fun: pdm-grp {
> +			mux-states = <&can_mux 0>;
> +		};
> +	};

Just to make sure: If both &flexcan2 and &micfil were enabled at the
same time, the existing pinctrl clash detection will also work for this
new pinctrl-multiplexer and point that out, right?

Thanks,
Ahmad

> +
>  	memory@40000000 {
>  		device_type = "memory";
>  		reg = <0x0 0x40000000 0 0xc0000000>,
> @@ -446,7 +465,7 @@ &flexcan1 {
>  
>  &flexcan2 {
>  	pinctrl-names = "default";
> -	pinctrl-0 = <&pinctrl_flexcan2>;
> +	pinctrl-0 = <&pinctrl_flexcan2>, <&can_fun>;
>  	phys = <&flexcan_phy 1>;
>  	status = "disabled";/* can2 pin conflict with pdm */
>  };
> @@ -712,7 +731,7 @@ &lcdif3 {
>  &micfil {
>  	#sound-dai-cells = <0>;
>  	pinctrl-names = "default";
> -	pinctrl-0 = <&pinctrl_pdm>;
> +	pinctrl-0 = <&pinctrl_pdm>, <&pdm_fun>;
>  	assigned-clocks = <&clk IMX8MP_CLK_PDM>;
>  	assigned-clock-parents = <&clk IMX8MP_AUDIO_PLL1_OUT>;
>  	assigned-clock-rates = <196608000>;
> 

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