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i.mx6q plus uart FIFO overrun

Question asked by lin ya on Jul 24, 2017
Latest reply on Oct 10, 2017 by lin ya

I migrant cpu from i.mx6q to i.mx6 plus.

the software is yocto imx_3.14.52_1.1.0_ga

I test the same software, except device tree file, on both platform.

The same rootfs and zImage,  different device tree file with the same uart config.

on i.mx6q the uart run well but i.mx6q plus encounter uart fifo overrun.

the message is like bellow:

 

[ 424.287781] imx-uart 21ec000.serial: Rx FIFO overrun
[ 425.287739] imx-uart 21ec000.serial: Rx FIFO overrun
[ 426.287685] imx-uart 21ec000.serial: Rx FIFO overrun
[ 427.287632] imx-uart 21ec000.serial: Rx FIFO overrun
[ 428.287580] imx-uart 21ec000.serial: Rx FIFO overrun
[ 429.287530] imx-uart 21ec000.serial: Rx FIFO overrun
[ 430.287476] imx-uart 21ec000.serial: Rx FIFO overrun

 

I check the message:

iMX6Quad uart RX Fifo Overrun 

 

My overall bus load is 78% on i.mx6q,

But i.mx6q plus is just 43%, it far bellow i.mx6q.

This is no look like bus load issue.

What is root cause ? 

 

MMDC new Profiling results:
***********************
Measure time: 500ms
Total cycles count: 264066104
Busy cycles count: 114651213
Read accesses count: 8899358
Write accesses count: 6043767
Read bytes count: 422906320
Write bytes count: 266389076
Avg. Read burst size: 47
Avg. Write burst size: 44
Read: 806.63 MB/s / Write: 508.10 MB/s Total: 1314.73 MB/s
Utilization: 37%
Overall Bus Load: 43%
Bytes Access: 46

 

I try to change the uart Qos.

The uart is connect to AIPS_TZ1.

I check the applications processor reference manual chapter 47.3.4  NIC-specific parameters

But there is no AIPS on table 47-5

How can I change the Qos for uart?

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