Enable UART3 on imx8qxp-mek

[carlo_p]

Hi,

I'm trying to enable the UART3, which, if I'm right, is the one who access the MikroBus Header on the connected MCIMX8-8X motherboard.

In order to do this, according to the schematics, first I had to modify the position of the the 0 ohm resistors R1 and R2, located on the top view of the imx8qxp-mek. This was necessary because, by default, they were connected in order to enable the BB_AUDIO_UART3 signal, instead of the plain UART.

After that, are there any software configuration I need to make (maybe in the DTS files) for having the device ttyLP3 (maybe differently named) show in my devices list?

[igorpadykov]

Hi carlo_p

for lpuart3 dts example one can look at:

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8x-mek.dt...

Best regards
igor

[carlo_p]

Could you help me please? @igorpadykov ?

[igorpadykov]

you are right it is enabled by default, no modifications are needed.

 

Best regards
igor

[carlo_p]

ok, then how is it possible that ttyLP3 doesn't show in /dev/ ?

[igorpadykov]

one can try with Demo Images from link:

https://www.nxp.com/design/software/embedded-software/i-mx-software/embedded-linux-for-i-mx-applicat...

Best regards
igor

[carlo_p]

I'm sorry but this isn't very helpful. I've built the image with yocto without any modification in dts files.

File imx8x-mek.dtsi is identical to the one you've linked. Any idea about something that would prevent ttyLP3 to show in /dev ?

[nolan_zinn]

I don't know if you've resolved this yet, but if you're building rpmsg, then lpuart3 is disabled.  See https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8x-mek-rp...:

&lpuart3 {
	status = "disabled";
};

&uart3_lpcg {
	status = "disabled";
};

If this is your problem, you should consider building the non-rpmsg image from yocto.

Regards,

Nolan

[carlo_p]

Hi, thank you.

The link you posted is the default version of file imx8x-mek.dtsi.

I don't understand which are the modifications to make...