Pine64-mainline: Can't change console to ttyS3

[linda 3]

Hi,

I've tried to change the default console from ttyS0 to ttyS3, using the mainline kernel but I don't get it to work.

 

 

Modifying boot.cmd I managed to change the tty's baudrate like this:

"if test "${console}" = "serial" || test "${console}" = "both"; then setenv consoleargs "${consoleargs} console=ttyS0,38400"; fi"

 

after recompiling with "mkimage -C none -A arm -T script -d /boot/boot.cmd /boot/boot.scr"

it gave me an 38400-baud-output begining with line "Loading, please wait...starting version 229"

 

But changing the settings to use ttyS3 does not work at all:

"if test "${console}" = "serial" || test "${console}" = "both"; then setenv consoleargs "${consoleargs} console=ttyS3,38400"; fi"

after recomililation ttyS3.is simply dead.

 

Using the following string works like a charm with the legacy kernel!

"if test "${console}" = "serial" || test "${console}" = "both"; then setenv consoleargs "${consoleargs} console=ttyS3,38400n8"; fi"

(The "n8" suffix after the baudrate does not seem to matter at this point.)

 

I tested the following armbian versions with the same result.

5.27.170614 nightly Ubuntu 16.04.2 LTS 4.11.1-sun50iw1  and

5.31.170619 nightly Ubuntu 16.04.2 LTS 4.11.1-sun50iw1

 

 

 

[martinayotte 678]

You will need to tweak the Main DT to enable the uart3...

 

[linda 3]

Is the problem resolved in the following updates?

The modification of the serial console to ttyS3 is absolutly essential for me. With the legacy kernel it worked without any problems..

[zador.blood.stained 764]

6 minutes ago, linda said:

Is the problem resolved in the following updates?

No, because it's not a problem. Peripherials like UART, I2C, SPI are disabled by default and pins are configured as plain GPIO, and DT overlays can be used to change this.

[linda 3]

Thank you very much for pointing me in the right direction.

I wasn't aware of the possibility to apply overlays to the device tree.

And I didn't want to change the master DT because of loosing my changes in case of updates coming from armbian.

 

Consulting the armbian documentation https://docs.armbian.com/User-Guide_Allwinner_overlays/

I found out there are already overlays supplied for various purposes and I just used: "/boot/dtb/allwinner/overlay/sun50i-a64-uart3.dtbo".

 

After activating the overlay in "ArmbianEnv.txt" I was done. Great!