IMX8QXP Kernel not working from LPUART1

[mdmosaddekhossa]

Hello NXP Team,

Currently we are facing issue to boot the kernel in our iMX8QXP custom board. Via fastboot we are flashing the linux kernel and device tree from u-boot. When we try to boot the kernel no response is coming from the LPUART1. We are using LPUART1 instead of LPUART0 from reference MEK board. 

Kernel version:

4.19.35_1.1.0

Kernel Device Tree Using LPUART1:

chosen {
bootargs = "console=ttyLP1,115200 earlycon=lpuart32,0x5a070000,115200";
stdout-path = &lpuart1;
};

&iomuxc {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_hog>;

imx8qxp-sthu {

pinctrl_hog: hoggrp {
fsl,pins = <
>;
};

pinctrl_lpuart1: lpuart1grp {
fsl,pins = <
SC_P_UART1_RX_ADMA_UART1_RX 0x06000020
SC_P_UART1_TX_ADMA_UART1_TX 0x06000020
>;
};

};

};

&pd_dma_lpuart1 {
debug_console;
};

&lpuart1 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_lpuart1>;
status = "okay";
};

Defconfig:

Check the attachment.

Problem:

These `/dma-controller@5a1f0000, 48852` messages come from u-boot. And `u-boot` successfully transfers control to linux.

But nothing comes out from Kernel lpuart1.

[igorpadykov]

Hi Mosaddek

one can look at

https://community.nxp.com/thread/493688 

Best regards
igor
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[mdmosaddekhossa]

Hallo Igor,

Thanks for the reply. According to your answer in the thread chaning the Debug port i.MX8QXP , my u-boot has been configured exactly in same way. My u-boot lpuart1 is working. You can also check the unimog_imx8qxp.c file.

igorpadykov‌ as mentioned by you in the thread,

Then you'll need to make similar changes in the U-Boot device tree: arch/arm/dts/fsl-imx8qxp*.dts*. MUX and clocks should be configured, though you might need to enable (status = "okay";) lpuart3. Don't forget to include CONFIG_FSL_LPUART=y in your defconfig file.

The SOC device tree file provided from NXP uses pd_dma2_chan11 which is only the tx line dma. I have changed it to "pd_dma_lpuart1"

lpuart1: serial@5a070000 {
compatible = "fsl,imx8qm-lpuart";
reg = <0x0 0x5a070000 0x0 0x1000>;
interrupts = <GIC_SPI 346 IRQ_TYPE_LEVEL_HIGH>;
interrupt-parent = <&wu>;
clocks = <&clk IMX8QXP_UART1_CLK>,
<&clk IMX8QXP_UART1_IPG_CLK>;
clock-names = "per", "ipg";
assigned-clocks = <&clk IMX8QXP_UART1_CLK>;
assigned-clock-rates = <80000000>;
power-domains = <&pd_dma2_chan11>;
dma-names = "tx","rx";
dmas = <&edma2 11 0 0>,
<&edma2 10 0 1>;
status = "disabled";
};

## My Device Tree ## in U-boot

pinctrl_lpuart1: lpuart1grp {
fsl,pins = <
SC_P_UART1_RX_ADMA_UART1_RX 0x06000020
SC_P_UART1_TX_ADMA_UART1_TX 0x06000020
>;
};

&lpuart1 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_lpuart1>;
status = "okay";
};

After correcting the LPUART1 dma from the device tree file. Now the Kernel is working.