LayerscapeのトピックRe: LX2160a linux : UART Configuration /dev/ttyAMA1

LX2160a linux : UART Configuration /dev/ttyAMA1

SebastienV — Tue, 20 Jun 2023 14:49:03 GMT

We are using the LX2160a on our VPX SBC VX6124 ( https://www.kontron.com/en/products/vx6124/p159844), we are facing an issue when the try to change the baudrate on the /dev/ttyAMA1 UART, we get the stty error : stty: /dev/ttyAMA1: cannot perform all requested operations

It is similar with the issue below, but in our case it is not on the console port.

https://community.nxp.com/t5/Layerscape/LX2160a-linux-UART-configuration/m-p/1522691#M11161

We do not understand why we cannot be changed by user space software, because the /dev/ttyAMA1 UART is not our console port. Could you explain why the 2 UARTs port are impacted by this limitation?

It is with amba pl011 uart driver using LSDK 21.08.

Sincerely,

Re: LX2160a linux : UART Configuration /dev/ttyAMA1

Oswalag — Fri, 23 Jun 2023 21:57:55 GMT

Hello,

Modify the baud rate from userspace is not possible.

As the similar case shared by you explain it, the SBSA UART has a fixed baud rate and flow control setting which cannot be changed by user space software, even if it is your console port or not.

Re: LX2160a linux : UART Configuration /dev/ttyAMA1

SebastienV — Thu, 29 Jun 2023 08:16:13 GMT

knowing this information, what is the right way to configure this speed? is it possible to configure something in the device tree? or is it too late in the boot process?

Cordialement,

Re: LX2160a linux : UART Configuration /dev/ttyAMA1

Oswalag — Fri, 30 Jun 2023 20:02:35 GMT

The configuration is not placed in the dts, Changes must be done in firmware for changing baud rate in plat_def.h,

In atf source code plat/nxp/soc-lx2160a/lx2160ardb/plat_def.h

Please try it and let me know if it works for you.