Hi to all,
I have run rpi 3b with vanilla kernel until today. Serial port was available and usable - it looks like this:
crw-rw---- 1 root uucp 4, 65 15. Aug 12:09 /dev/ttyS1
But vanilla kernel seems not to support rpi hardware perfectly - rpi often stops with a kernel panic. So I decided to switch to linux-rpi kernel. Swapping was successful - system aarch64 is running now with linux-rpi kernel. Of course I looked at /boot/config.txt and /boot/cmdline.txt and adapted my changes which were saved in *.pacsave files.
After reboot the serial port /dev/ttyS1 was vanished - but I get an /dev/ttyAMA0. It looks different:
crw-rw---- 1 root uucp 204, 64 17. Aug 09:39 /dev/ttyAMA0
and - badly - it does no longer work. I have checked /boot/cmdline.txt if anything "serial" was present there but it was not. I can write in the device and read from it - but it is the same as if I use /dev/null. I have looked at the RXD and TXD pins using a scope - but they are "silent". I am missing the negative level. It looks as /dev/ttyAMA0 is mapped to something different than the serial port.
Here my config.txt-settings related to uart:
$this->bbcode_second_pass_code('', '
# enable serial port
core_freq=250
enable_uart=1
')
EDIT:
There are both /proc/device-tree/aliases/uart0 and /proc/device-tree/aliases/uart1 present - but ttyS1 is not created.
Now I am stuck at this - I need the serial port...