Based on this answer, I am trying to change the console serial port from UART1 to UART3 (pins 19 and 21 based on Table 5-20 Colibri iMX7 reference doc).
I have rebuilt U-Boot after applying the below diff. Linux kernel is now correctly using UART3 for serial console (probably because of console=ttymxc2 environment variable which is changed correctly in U-Boot).
However, U-Boot is still using UART1 for its console and doesn’t output anything to UART3.
By comparing the codes for iMX6 modules, I have found a three major differences that could be the cause of this issue. The cause of this issue could be them, but also there could be a simple configuration that I am missing.
1. CONFIG_MXC_UART_BASE
The colibri_imx6.h defines the following macro:
#define CONFIG_MXC_UART_BASE UART3_BASE
I wonder if a similar line should be added in colibri_imx7_emmc.h. Currently, CONFIG_MXC_UART_BASE is not defined in this file.
2. setup_dtemode_uart
The colibri_imx6.c calls setup_dtemode_uart function that sets up some registers, but colibri_imx7.c doesn’t have such function. Is this function needed for imx7?
static void setup_dtemode_uart(void)
{
setbits_le32((u32 *)(UART1_BASE + UFCR), UFCR_DCEDTE);
setbits_le32((u32 *)(UART2_BASE + UFCR), UFCR_DCEDTE);
setbits_le32((u32 *)(UART3_BASE + UFCR), UFCR_DCEDTE);
clrbits_le32((u32 *)(UART1_BASE + UCR3), UCR3_DCD | UCR3_RI);
clrbits_le32((u32 *)(UART2_BASE + UCR3), UCR3_DCD | UCR3_RI);
clrbits_le32((u32 *)(UART3_BASE + UCR3), UCR3_DCD | UCR3_RI);
}
3. mxc_serial_platdata
Again in colibri_imx6.c, the uart port is defined as a U-Boot device using platform data:
static struct mxc_serial_platdata mxc_serial_plat = {
.reg = (struct mxc_uart *)UART1_BASE,
.use_dte = true,
};
U_BOOT_DEVICE(mxc_serial) = {
.name = "serial_mxc",
.platdata = &mxc_serial_plat,
};
Isn’t such thing necessary for iMX7 too?
Here is full diff of the changes I have made to U-Boot source:
diff --git a/board/toradex/colibri_imx7/colibri_imx7.c b/board/toradex/colibri_imx7/colibri_imx7.c
index a8d8dbd..5f71967 100644
--- a/board/toradex/colibri_imx7/colibri_imx7.c
+++ b/board/toradex/colibri_imx7/colibri_imx7.c
@@ -59,11 +59,9 @@ int dram_init(void)
return 0;
}
-static iomux_v3_cfg_t const uart1_pads[] = {
- MX7D_PAD_UART1_RX_DATA__UART1_DTE_TX | MUX_PAD_CTRL(UART_PAD_CTRL),
- MX7D_PAD_UART1_TX_DATA__UART1_DTE_RX | MUX_PAD_CTRL(UART_PAD_CTRL),
- MX7D_PAD_SAI2_TX_BCLK__UART1_DTE_CTS | MUX_PAD_CTRL(UART_PAD_CTRL),
- MX7D_PAD_SAI2_TX_SYNC__UART1_DTE_RTS | MUX_PAD_CTRL(UART_PAD_CTRL),
+static iomux_v3_cfg_t const uart3_pads[] = {
+ MX7D_PAD_UART3_RX_DATA__UART3_DTE_TX | MUX_PAD_CTRL(UART_PAD_CTRL),
+ MX7D_PAD_UART3_TX_DATA__UART3_DTE_RX | MUX_PAD_CTRL(UART_PAD_CTRL),
};
static iomux_v3_cfg_t const usdhc1_pads[] = {
@@ -208,7 +206,7 @@ static void setup_iomux_fec(void)
static void setup_iomux_uart(void)
{
- imx_iomux_v3_setup_multiple_pads(uart1_pads, ARRAY_SIZE(uart1_pads));
+ imx_iomux_v3_setup_multiple_pads(uart3_pads, ARRAY_SIZE(uart3_pads));
}
#ifdef CONFIG_FSL_ESDHC
diff --git a/include/configs/colibri_imx7_emmc.h b/include/configs/colibri_imx7_emmc.h
index 957d420..642da95 100644
--- a/include/configs/colibri_imx7_emmc.h
+++ b/include/configs/colibri_imx7_emmc.h
@@ -125,7 +125,7 @@
NFS_BOOTCMD \
SD_BOOTCMD \
"boot_file=zImage\0" \
- "console=ttymxc0\0" \
+ "console=ttymxc2\0" \
"defargs=\0" \
"fdt_board=eval-v3\0" \
"fdt_fixup=;\0" \