imx6 serial port rx problem

[zhanxiaozhang]

We use imx6q ,android 4.4.3 kernel 3.10.53.

when high temperature working (under 80°c). After about 3 hours ,uart can not receive any data ,but tx works well.

we test 4 pcs at the same time ,1/4 meet this issue (the same one failed ).

Is there anybody meet the issue?

[igorpadykov]

Hi zhanxiaozhang

at high temperatures linux decrease processor clocks as described in

Chapter 26 Thermal Driver attached Linux Manual. Just for test one can try to

disable bus frequency driver using Chapter 25 Dynamic Bus Frequency Driver.

AN4579 i.MX 6 Series Thermal Management Guidelines describes thermal

management solutions:

https://www.nxp.com/docs/en/application-note/AN4579.pdf 

Best regards
igor
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[zhanxiaozhang]

you mean maybe the high temperature cause the hardware problem,not firmware releated?

[danielberhe]

Hi zhanxiaozhang,

Were you able to get the bottom of this problem? I'm seeing similar issues on my custom board based on IMX6 Solo. I was running a test with heavy CPU load (>85%), after about 1.5 hours, the IMX got too hot and crashed. After this, I can't get any sensible UART TX trace but the RX is fine. Even though I can't read it, I know the RX is working because I sent a boot command (on uboot) and the board was booting Linux.

I looked at the TX line using a scope and it looks like it is struggling to pull low. Any ideas?

Regards,

Daniel