i.MX Processorsのトピックimx6 UART issue on 5.4.24 kernel

imx6 UART issue on 5.4.24 kernel

zc_tee — Mon, 19 Oct 2020 05:04:14 GMT

Hi all,

I am porting my I.MX6 platform kernel from 4.9.11 to 5.4.24, and face some weird issue on the UART port

after i port the code and my device tree, I manage to boot up my machine. Then I tried to read some data from another subcpu which is connected to ttymxc2.

In console, I tried to cat /dev/ttymxc2, but it returns me with some text that seems like system related information as below:

I tried to do a stty then cat, it returns me with another type of information, which seems to be like cat /proc/filesystems plus something else as below:

I cannot understand why is this happening. It seems like the ttymxc device is mixed up with /proc/ information. Can anybody advise?

One thing is that the system is working fine in kernel 4.9.11. Only change is changing the kernel from 4.9.11 to 5.4.24.

By the way, i am using same bootloader 2017.03 for both the 4.9.11 and 5.4.24 kernel. I suppose 5.4.24 kernel can work well with 2017.03 uboot?

Thank you.

Regards,

Tee

Re: imx6 UART issue on 5.4.24 kernel

igorpadykov — Mon, 19 Oct 2020 07:20:53 GMT

Hi Tee

you are right, reason may be in uboot, recommended to use

uboot version (v2020.04) as listed in Release Notes of each BSP described on

https://www.nxp.com/design/software/embedded-software/i-mx-software/embedded-linux-for-i-mx-applications-processors:IMXLINUX?tab=In-Depth_Tab

https://source.codeaurora.org/external/imx/uboot-imx/tree/?h=imx_v2020.04_5.4.24_2.1.0

Best regards
igor

Re: imx6 UART issue on 5.4.24 kernel

zc_tee — Mon, 19 Oct 2020 07:30:44 GMT

Hi Igor,

After doing some searching online, i tried to disable the serial port dma in device tree

Then my machine's UART port works.

I think i will disable the UART dma for now and test further. Do you forsee any issue disabling the UART's dma?

Regards,

Tee

Re: imx6 UART issue on 5.4.24 kernel

igorpadykov — Mon, 19 Oct 2020 09:49:26 GMT

Hi Tee

usually dma is disabled for console port.

Best regards
igor

Re: imx6 UART issue on 5.4.24 kernel

zc_tee — Tue, 20 Oct 2020 01:49:15 GMT

Hi Igor

Thank you. I will proceed with disabling UART dma.