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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#define CONFIG_MXC_UART_BASE UART4_BASE_ADDR
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";
};
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
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
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
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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