Enable gpio serial port NOT hosting linux console

#1

Hi there, new to this board and Radxa.

I’m trying to use the serial port on the 40 pin GPIO header at pins 8 and 10, but I do NOT want the linux console there. I just want to be able to open the serial port and use it normally.

I’ve tried modify the kernel boot parameters, but I’m flying a little blind here.

# Execute "update_extlinux.sh" after changing file /boot/config.txt.

#cmdline: earlycon=uart8250,mmio32,0xfeb50000 console=ttyFIQ0 console=tty1 consoleblank=0 loglevel=0
cmdline: earlycon=uart8250,mmio32,0xfeb50000 loglevel=0


dtoverlay=rk3588-uart7-m2

Do I comment out the dtoverlay? Use a different one? Can I find a mapping of what uart7 and m2 mean? The dtoverlay page doesn’t even list the rk3588 overlays.

I should mention that I am trying to bring up a gpio “hat” that I had previously developed for the pi devices. This had communicates over serial at 1Mb/s. I have noticed that I can see garbled communications from my device on /dev/ttsyFIQ0. It looks like it is running at the wrong speed. I have tried using stty and other methods to set the speed to 1000000, but it fails. It looks like the speed of this port is somehow locked at 115200?

Thanks!

#2

Replying to my own post, maybe it will be useful to someone else.

The following seems to have made the gpio pins 8,10 port appear as /dev/ttyS2 and it works normally:

dtoverlay=rk3588-uart2-m0
1 Like
#3

Just for information, i disabled uart2 linux default console like u explained. It worked well.
But if u wanted to use another uart as console u need to downgrade the speed in cmdline.

For console

cmdline: earlycon=uart8250,mmio32,0xfeb50000 console=ttyS3,115200 console=tty1 consoleblank=0 loglevel=0

For rootfs

cmdline: panic=10 rootwait rw init=/sbin/init rootfstype=ext4

Docker optimizations

cmdline: cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory swapaccount=1

For RK3588

cmdline: irqchip.gicv3_pseudo_nmi=0

cmdline: switolb=1
cmdline: coherent_pool=2M

dt overlay line: started with “dtoverlay=”. One dt overlay one line.

dtoverlay=rk3588-uart2-m0
dtoverlay=rk3588-uart3-m1
dtoverlay=rk3588-spi0-m2-cs0-spidev