iMX6Q Sudden Freeze with EXAR Linux USB Serial Driver

[viswanathan_m]

Hi,

We are using linux 3.14.61 imx6 BSP and also tried with linux 4.9.88 BSP for testing the USB-Serial controller.

We are using the EXAR USB serial controller and testing with the USB-Serial test application  (writing the data continuously). We are checking through the serial port console from the host PC. But after sometime i.e 20 minutes the system is not responding and it looks frezzed.There is no kernel panic observed or no error messages in console. 

we tried to alloc buffers in EXAR driver with GFP_DMA | GFP_ATOMIC flag @(instead of existing GFP_KERNEL) we could see some improvements i.e hang failure happens later than 40 minutes. The issue observed in both SMP and NO SMP cases.

We have added few kernel options for debugging, but we are not getting any logs during the time of hang.

We have enabled ftrace in the kernel and captured logs.

Please find the attached ftrace log files which we have tested with 3.14.61 linux kernel and 4.9.88 linux kernel.

1. Could you please confirm if there is any issues similar to this?

2. Please confirm if there is any bug fix/ ERRATA available?

3. Is there any imx6 firmware update available?

4. Any debugging option available in imx6  kernel.

IMX6 Part Num: MCIMX6Q7CVT08AC

QCN1633

msia fgcnqy

Regards

Viswanathan M

[igorpadykov]

Hi Viswanathan

one can consider app note for these devices and issues reported by other developers

USB BASICS FOR THE EXAR FAMILY

https://www.exar.com/appnote/an213_033111.pdf 

Bug #1645591 “Driver for Exar USB UART” : Bugs : linux package : Ubuntu 

vizzini driver (Atlys) for Exar XR21V1414 USB UART is not reliable · Issue #146 · timvideos/HDMI2USB... 

Best regards
igor
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[viswanathan_m]

Thanks for the link.

Could you please confirm if any latest ARM ERRATA available? Please confirm the latest uboot version available for imx6? We are using uboot version 2014.v7

[igorpadykov]

uboot-imx - i.MX U-Boot 

linux-imx - i.MX Linux kernel 

Docs

i.MX Software|NXP 

i.MX6Q errata

https://www.nxp.com/docs/en/errata/IMX6DQCE.pdf 

for "latest ARM ERRATA" please apply to arm (Contact Arm Support – Arm )

[viswanathan_m]

Hi,

We are still facing the sudden hang of the system.

But during our debugging, we observed that STS_FATAL error bit 4 of USBSTS register is being set during the hang.

In an another instance, we observed the bit 1 of USBSTS register, STS_ERR (Host System Error is Set) during the hang.

Now it is very consistent with STS_ERR/STS_FATAL error bit set during the system hang.

Is this due to hardware issue or software ?  We are debugging on this now. Any specific way to debug reason for this STS_FATAL and STS_ERR?

Thank you.

Regards

Viswanathan M

[viswanathan_m]

Hi,

Any pointers to debug on this STS_FATAL and STS_ERR of USB Status registers?

[JohnDoe2]

I am having the same problem as you.

Did you find a solution and the cause?