SK-AM62: Adopt Pin E23 & D24 pins as Tx and Rx of UART and make both loopback, however it's not workable

Hi Kylix,

Please try to disable the sdhci2 node in the kernel device tree to see if this resolves the issue.

Hi Bin,

After disabling all the sdhci2 node related to am62-serial in the kernel device tree, this issue still can't be resolved.
The below are the modification for removing sdhci2:

Best Regards,
Kylix

Hi Kylix,

In your first post above, you only explained the pinmux settings for uart5, but did you add this pinmux setting to the main_uart5 node, and enable main_uart5 in device tree?

If so, please attach the kernel boot log.

Hi Bin,

I added the pinmux setting to the main_uart5 node, and enable it.

The below is my kernel boot log.
Boot_UART5-wo-RTSDTS.log

Best Regards,
Kylix

Hi Kylix,

Please show the commands and log of your UART5 test and explain how it "doesn't work".

Hi Bin,

Please refer to the log as below:

root@Triton:~# dmesg | grep ttyS
[    0.000000] Kernel command line: console=ttyS2,115200n8 earlycon=ns16550a,mmio32,0x02800000 root=PARTUUID=c8c70a08-02 rw rootfstype=ext4 rootwait
[    1.125275] printk: console [ttyS2] disabled
[    1.129719] 2800000.serial: ttyS2 at MMIO 0x2800000 (irq = 27, base_baud = 3000000) is a 8250
[    1.138490] printk: console [ttyS2] enabled
[    1.158254] 2810000.serial: ttyS1 at MMIO 0x2810000 (irq = 28, base_baud = 3000000) is a 8250
[    1.167896] 2850000.serial: ttyS5 at MMIO 0x2850000 (irq = 29, base_baud = 3000000) is a 8250
root@Triton:~# stty -F /dev/ttyS5 -echo -onlcr 115200
root@Triton:~# cat /dev/ttyS5 &
[1] 939
root@Triton:~# echo "Test" > /dev/ttyS5
root@Triton:~# 

Because Rx & Tx pins had been loopback.
We expect that it will return "Test" string which we inputted.
But this string isn't shown.

Hi Kylix,

If you use a scope or a logic analyzer to probe the TX line, do you see the waveform of the transfer?