IMX6 overrun on UART (RS)

[sylvainlehenaff]

Good evening community,

I am currently having some issue with a SMARC from Kontron used with a kernel 3.10.17. The smarc is based on a IMX6Q working at 1GHz.

I am using an RS422 on an UART to exchange some data between the IMX6 and another board. When  the UART is only used, everything is fine but when I am using the ethernet link at the same time I start to observe some overrun at the IMX_uart driver level. These overrrun corrupting the data exchanged, my application ends in a nice crash.

I  tryied to change the speed on the UART with no real success. I have seen that some problem have been identified when using DMA but this not my case.

I have found a way to reduce the amount of overrrun by changing affinity of the IRQ associated to the uart but this is not a real answer to the problem.

I don't understand these overrun, the amount of data is quite low.....

Does anybody have observed such overrun ? any solution ?

NB) I cannot changed my kernel due to SMARC specificies (Kontron did not yet upgrade their BSP for it)

Regards

Sylvain

[igorpadykov]

Hi Sylvain

due to bus bandwidth limitation there may be overruns, this is expected

behaviour. In general one can use sending data in packets, protecting with

crc control check. If overruns occur, transmitting side can repeat data.

Other option - decrease overall bus load - this may be done decreasing

number of running applications, use more fast processor or decreasing

ethernet speeds.

Best regards

igor

-----------------------------------------------------------------------------------------------------------------------

Note: If this post answers your question, please click the Correct Answer button. Thank you!

-----------------------------------------------------------------------------------------------------------------------

[sylvainlehenaff]

Hi,

I have seen similar information regarding effect of bandwidth, however, I am a bit supprised because I am only using 1 RS link + 1 Ethernet and I can generate these overrun.

I will check with a new kernel as soon as I can.

regards,

Sylvain