2022543_en-US

[#1]

Why doesn't uart2 node include dmas in imx8mm.dtsi?

Hi.

In imx8mm.dtsi, uart2 node don't include the dmas.

But other uart node (1. 2 and 4) include the dmas.

Why? and What is the impact of not including the dmas?

■ imx8mm.dtsi

https://github.com/torvalds/linux/blob/master/arch/arm64/boot/dts/freescale/imx8mm.dtsi

uart1: serial@30860000 {

compatible = "fsl,imx8mm-uart", "fsl,imx6q-uart";

reg = <0x30860000 0x10000>;

interrupts = ;

clocks = <&clk IMX8MM_CLK_UART1_ROOT>,

<&clk IMX8MM_CLK_UART1_ROOT>;

clock-names = "ipg", "per";

dmas = <&sdma1 22 4 0>, <&sdma1 23 4 0>;

dma-names = "rx", "tx";

status = "disabled";

};

uart3: serial@30880000 {

compatible = "fsl,imx8mm-uart", "fsl,imx6q-uart";

reg = <0x30880000 0x10000>;

interrupts = ;

clocks = <&clk IMX8MM_CLK_UART3_ROOT>,

<&clk IMX8MM_CLK_UART3_ROOT>;

clock-names = "ipg", "per";

dmas = <&sdma1 26 4 0>, <&sdma1 27 4 0>;

dma-names = "rx", "tx";

status = "disabled";

};

uart2: serial@30890000 {

compatible = "fsl,imx8mm-uart", "fsl,imx6q-uart";

reg = <0x30890000 0x10000>;

interrupts = ;

clocks = <&clk IMX8MM_CLK_UART2_ROOT>,

<&clk IMX8MM_CLK_UART2_ROOT>;

clock-names = "ipg", "per";

status = "disabled";

};

Best Regards.

Re: Why doesn't uart2 node include dmas in imx8mm.dtsi?

Hello,

This is because UART2 is used for debug purposes. If you check the device tree, the debug UART port doesn't use DMA.

Best regards.