Utilization of additional serial ports and I2C busses on Tinkerboard S

[nkinar]

Hello,

 

I've used the Tinkerboard S (Rockchip RK3288) with the Armbian images available for download (https://www.armbian.com/tinkerboard/).  Currently, the /dev/ttyS4 serial port is not available unless CONFIG_SERIAL_8250_NR_UARTS=5 when the Linux kernel is built since the serial ports are populated in /dev starting with /dev/ttyS0 and the last serial port to be populated is /dev/ttyS4.  By default,  CONFIG_SERIAL_8250_NR_UARTS=4.  Some additional kernel settings are required to ensure that all of the available serial ports can be utilized.  Moreover,  I had to activate I2C4 in the device tree overlay using the Armbian configuration utility (https://docs.armbian.com/User-Guide_Armbian-Config/) since I2C4 is required for my application.  I also built the kernel and the BSP using the excellent instructions posted on the Ambian website.

 

Would a patch be good to contribute?  I can contribute this myself if required.  I am wondering if there is a reason (design philosophy) for not supporting all of the serial ports and some of the devices listed in the device pinout.  Perhaps it would be good to ensure that all or most of the features listed in the pinout work out of the box on the supported images?

 

 

Edited March 2, 2022 by nkinar
added info

[MichaIng]

Am 2.3.2022 um 18:07 schrieb nkinar:

I had to activate I2C4 in the device tree overlay using the Armbian configuration utility (https://docs.armbian.com/User-Guide_Armbian-Config/)

 

I'm confused. Do you have device tree overlays shipped with the Armbian kernel, i.e. does /boot/dtb/overlay exist? I don't see any, neither on latest Armbian image, nor in "current" "rockchip" kernel and dtb packages. Still armbianEnv.txt has the "overlays" setting defined with a bunch of overlays, but it must be a noop. Or am I overlooking something, or do you mean you created an overlay manually? But how is this possible via armbian-config, which only lists the overlays present in /boot/dtb/overlay?

[nkinar]

Thanks, MichaIng.  After installation, I had to use the armbian-config utility, and under System -> DTC,  an editor is opened to edit current.dts.   I2C4 is listed as 0xff160000,  and in the DTF, I had to change status="okay" for this I2C port to work. 

 

Also, I had to re-compile the Linux kernel and set CONFIG_SERIAL_8250_NR_UARTS=4 to be able to use /dev/ttyS4. 

[jock]

Hello, I can confirm that overlay directory was missing, there is a pull request that is going to be merged soon (https://github.com/armbian/build/pull/3558) to restore it.

 

About the kernel config option, it can be indeed done easily.

[nkinar]

Thanks, jock!  Great to have this.  Also, it will be good to have the kernel config option set as default so that the /dev/ttyS4 serial port is available on the minimal image.

[jock]

Okay, everything is now merged into mainline

[nkinar]

10 hours ago, jock said:

Okay, everything is now merged into mainline

Thanks, that is great.