topic i.MX8M Mini Boot issue-UART4 in i.MX Processors

i.MX8M Mini Boot issue-UART4

shruthi_subrama — Fri, 26 Jul 2019 10:45:58 GMT

Hi,

We are doing i.MX8M Mini based custom Board bring up.

The UART4 is used as debug UART in our custom board, with this we are getting SPL and ATF debug prints, but U-boot debug prints are not getting.

If we configure UART2 as debug UART in our custom board (both SW and HW), the U-boot prints are coming in debug console.

1)Is there any limitation for debug UART that only UART2 must be configured for debug console? Please clarify.

2)For your your information ,following changes are made to configure UART4 as debug console. Please Confirm this is correct.

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File Name: “include/configs/imx8mm_evk.h”

#define CONFIG_MXC_UART_BASE UART4_BASE_ADDR

DTSI and DTS file changes

aliases {

serial3 = &uart4;

};

uart4: serial@30a60000 {

compatible = "fsl,imx8mm-uart",

"fsl,imx6q-uart", "fsl,imx21-uart";

reg = <0x0 0x30a60000 0x0 0x10000>;

interrupts = <GIC_SPI 29 IRQ_TYPE_LEVEL_HIGH>;

interrupt-parent = <&gpc>;

clocks = <&clk IMX8MM_CLK_UART4_ROOT>,

<&clk IMX8MM_CLK_UART4_ROOT>;

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

status = "disabled";

};

chosen {

bootargs = "console=ttymxc3,115200 earlycon=ec_imx6q,0x30a60000,115200";

stdout-path = &uart4;

};

iomux configureation

pinctrl_uart4: uart3grp {

fsl,pins = <

MX8MM_IOMUXC_UART4_RXD_UART4_DCE_RX 0x49

MX8MM_IOMUXC_UART4_TXD_UART4_DCE_TX 0x49

};

&uart4 { / console /

pinctrl-names = "default";

pinctrl-0 = <&pinctrl_uart4>;

status = "okay";

};

File name: “board/freescale/imx8mm_evk/imx8mm_evk.c”

static iomux_v3_cfg_t const uart_pads[] = {

IMX8MM_PAD_UART4_RXD_UART4_RX | MUX_PAD_CTRL(UART_PAD_CTRL),

IMX8MM_PAD_UART4_TXD_UART4_TX | MUX_PAD_CTRL(UART_PAD_CTRL),

};

Please support and guide us for this issue.

Thanks and Regards,

Shruthi Subramanian

Re: i.MX8M Mini Boot issue-UART4

igorpadykov — Fri, 26 Jul 2019 23:29:31 GMT

Hi Shruthi

one can follow sect.3.2.4 Further customization at system boot

attached Porting Guide, test uart4 in uboot and check with jtag its configuration in

imx8mm_evk.c\imx8mm_evk\freescale\board - uboot-imx - i.MX U-Boot

check #define CONFIG_MXC_UART_BASE in

imx8mm_evk.h\configs\include - uboot-imx - i.MX U-Boot

check that uart4 clock was enabled in CCM CCM_CCGR76 register.

Best regards
igor
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Re: i.MX8M Mini Boot issue-UART4

shruthi_subrama — Mon, 29 Jul 2019 15:36:49 GMT

Hi igor,

We checked the above points,software settings are proper still U-boot debug prints are not coming in UART4.

We checked with other UART also,(UART1,UART3),still we are getting SPL and ATF debug prints only and we are not getting U-boot debug prints.

If we configure UART2 as debug UART only(both software wise & Hardware wise), the U-boot prints are coming in debug console. Is UART2 is hardcoded for debug console in iMX8M Mini?

Please help and guide us.

Thanks and Regards,

Shruthi Subramanian

Re: i.MX8M Mini Boot issue-UART4

igorpadykov — Tue, 30 Jul 2019 00:42:16 GMT

Hi Shruthi

in uboot one can attach jtag and check uart4 register settings:

CCM_CCGR76, then write with jtag to UART4_UTXD one should see

output from uart4 TX_DATA.

Best regards
igor