Recently I compiled my own linux system using kernel 5.10.23, and I made modifications to the device tree in order to activate UART 1 PIN (9-24) and (9-26).
I have /dev/ttyS1 available for R/W operations and when I do
dmesg | grep serial
[ 2.945152] 44e09000.serial: ttyS0 at MMIO 0x44e09000 (irq = 20, base_baud = 3000000) is a 8250 [ 3.685189] 48022000.serial: ttyS1 at MMIO 0x48022000 (irq = 26, base_baud = 3000000) is a 8250 [ 3.703783] msm_serial: driver initialized
I tried to debug using a logic analyser so when I do
echo "TEST" > /dev/ttyS1
I got nothing Any ideas why ?