1、 问题描述

串口通讯异常, Log如下:


     mxs-auart mxs-auart.0: Unhandled status 520080 

     或

     mxs-auart mxs-auart.2: Unhandled status 520280 


2、问题分析

 2.1 硬件参数:


Freescale i.MX28 family
 
CPU:   454 MHz

BUS:   151 MHz

EMI:   205 MHz

GPMI:   24 MHz

DRAM:  128 MB

NAND:  Manufacturer      : Macronix (0xc2)

Device Code       : 0xf1

Cell Technology   : SLC

Chip Size         : 128 MiB

Pages per Block   : 64

Page Geometry     : 2048+64

ECC Strength      : 1 bits

ECC Size          : 512 B

Data Setup Time   : 5 ns

Data Hold Time    : 5 ns

Address Setup Time: 15 ns

GPMI Sample Delay : 6 ns

tREA              : 20 ns

tRLOH             : 4294967295 ns

tRHOH             : 4294967295 ns

Description       : MX30LF1G08AA

128 MiB


 2.2 Log 定位:

$KERNEL/drivers/serial/mxs-auart.c

	/* modem status interrupt bits are undefined
	after reset,and the hardware do not support
	DSRMIS,DCDMIS and RIMIS bit,so we should ingore
	them when they are pending. */
	if (istat & (BM_UARTAPP_INTR_ABDIS
		| BM_UARTAPP_INTR_OEIS
		| BM_UARTAPP_INTR_BEIS
		| BM_UARTAPP_INTR_PEIS
		| BM_UARTAPP_INTR_FEIS
		| BM_UARTAPP_INTR_RTIS
		| BM_UARTAPP_INTR_TXIS
		| BM_UARTAPP_INTR_RXIS
		| BM_UARTAPP_INTR_CTSMIS)) {
		dev_info(s->dev, "Unhandled status %x\n", istat);
	}

// 继续反查 宏定义
#define BM_UARTAPP_INTR_ABDIS	0x00000800
#define BM_UARTAPP_INTR_OEIS	0x00000400
#define BM_UARTAPP_INTR_BEIS	0x00000200
#define BM_UARTAPP_INTR_PEIS	0x00000100
#define BM_UARTAPP_INTR_FEIS	0x00000080
#define BM_UARTAPP_INTR_RTIS	0x00000040
#define BM_UARTAPP_INTR_TXIS	0x00000020
#define BM_UARTAPP_INTR_RXIS	0x00000010
#define BM_UARTAPP_INTR_DSRMIS	0x00000008
#define BM_UARTAPP_INTR_DCDMIS	0x00000004
#define BM_UARTAPP_INTR_CTSMIS	0x00000002
#define BM_UARTAPP_INTR_RIMIS	0x00000001


// 可知, 触发条件为
mxs-auart mxs-auart.0: Unhandled status 520080
#define BM_UARTAPP_INTR_FEIS	0x00000080

mxs-auart mxs-auart.2: Unhandled status 520280
#define BM_UARTAPP_INTR_BEIS	0x00000200


2.3   触发条件分析
        < .......  >



3、 解决方案

       修改 主从机 通讯波特率9600 为 115200
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