Uart read fdmonitor not working after few minutes

I am faced the issue in uart fdmonitor handler,uart baudrate 460800. uart get interrupt every 1 milli second.

  1. In fdmonitor handler when we report a le_event_Report function it will work few minute,
    after that fdmonitor handler is not calling.
  2. cat /dev/ttyHS1 is also not printing any data.
  3. If we remove le_event_Report function from the fdmonitor handler it will work fine.
  4. if we restart app it work again.

please attach the application here
Please also try in WP76 R10.1 as i don’t see problem with that, not sure if issue happened only with 1ms interrupt

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root@swi-mdm9x28-wp:~# cm info
Device: WP7608
IMEI: 35291309036xxxx
FSN: 3N050785621410
Firmware Version: SWI9X07Y_02.28.03.03 000000 jenkins 2019/05/21 03:33:04
Bootloader Version: SWI9X07Y_02.28.03.03 000000 jenkins 2019/05/21 03:33:04
MCU Version: 002.011
PRI Part Number (PN): 9908665
PRI Revision: 001.002
Carrier PRI Name: GENERIC
Carrier PRI Revision: 002.068_000
SKU: 1104194
Last Reset Cause: Reset, User Requested
Resets Count: Expected: 79 Unexpected: 0
root@swi-mdm9x28-wp:~# legato version

.c file*****

static mcuApp_t App1;
mcuApp_t* hApp = &App1;

int WriteToUart(const uint8_t *wBuf , uint32_t wLen)
int retLen;
int offset=0;
LE_INFO(“seraia fd:%d”, hApp->serialFd);

PRINTDATAINHEX(“UWRITE”, (uint8_t*)wBuf, wLen);
while(offset < wLen)
retLen = write( hApp->serialFd ,wBuf+offset ,wLen-offset);
if(-1 == retLen)
else if(retLen <= (wLen-offset))
offset = offset + retLen;
retLen = offset;
LE_INFO(“Uart write byte count:%d” ,retLen);

LE_INFO(“Uart Total write byte count:%d Recieved len:%d”,offset ,wLen);
LE_INFO("write to uart :%d ", retLen);
return retLen;

uint32_t fdmonitorCount=0;
uint32_t CheckMessageCount=0;
tm_Data_t ParseData;
void CheckMessageHdlr(void
LE_INFO("%s", func);
LE_INFO(“eventCount checkMessge:%d”, CheckMessageCount++);
ParseData = (tm_Data_t*)ctx;
PRINTDATAINHEX(“read data”, ParseData->Buf, ParseData->bLen);


  • AsyncRecvHandler () → Callback func for UART fd_monitor ,events(POLLIN).
    tm_Data_t tmpData;
    void AsyncRecvHandler (int fd, short event)
    int retval = -1;
    LE_INFO("%d %s %#x ",fd ,FUNCTION, event);

if((event & POLLIN))
LE_INFO(“eventCount fdmonitor:%d”,fdmonitorCount++);
memset(hApp->RxBuf, 0, sizeof(hApp->RxBuf) );
retval = read(fd, hApp->RxBuf, sizeof(hApp->RxBuf));

if(retval > 0 )

#if 1
memset(&tmpData, 0, sizeof(tmpData) );
tmpData.bLen = retval;
memcpy( &tmpData.Buf, hApp->RxBuf, retval);
le_event_Report(hApp->CheckMsgEvtId, &tmpData, sizeof(tmpData));//

if(event & POLLOUT)
le_fdMonitor_Disable(hApp->fdMonitorRef, POLLOUT);

if( (event & POLLRDHUP) || (event & POLLERR) || (event & POLLHUP))
LE_INFO(“event %#x”, event);
hApp->fdMonitorRef = le_fdMonitor_Create(“serial Comm”,
(le_fdMonitor_HandlerFunc_t) &AsyncRecvHandler,
LE_INFO("%s done", func);


  • OpenUart() → Func Open’s the uart and set the custom Baudrate,
  • And also the Set to read the 8 bit data sets the start bit and stop bit.
    int32_t OpenUart(void)
    struct termios tty;

LE_INFO(“OpenUart called”);
hApp->serialFd = open(MCU_UART1, O_RDWR | O_NONBLOCK| O_NDELAY);
if(hApp->serialFd < 0 ){
LE_ERROR(“mcu uart open failed : %d %s”, errno, strerror(errno));
return LE_FAULT;

LE_INFO("%s:%d",hApp->PortName, hApp->serialFd);
if (tcgetattr (hApp->serialFd, &tty) != 0) //Get attribute Prop
LE_INFO(“error %d from tcgetattr”, errno);
return LE_FAULT;

LE_INFO(“OpenUart Opened uartd. Modifyuing UART settings”);
cfsetospeed (&tty, BAUDRATE); // O/p Baudrate setting
cfsetispeed (&tty, BAUDRATE); // I/p baudrate setting

tty.c_cflag = (tty.c_cflag & ~CSIZE) | CS8; // 8-bit chars
tty.c_cflag |= (CLOCAL | CREAD); // ignore modem controls,(

cfmakeraw(&tty); // Make these options as default.
tcflush(hApp->serialFd , TCIOFLUSH); // Push the changes onto Uart File Descrriptor
if (tcsetattr (hApp->serialFd, TCSANOW, &tty) != 0) // Setting the Attributes
LE_INFO (“error %d from tcsetattr”, errno);
return LE_FAULT;

// Create monitor FD handle for activity, as defined by the events
LE_INFO(“OpenUart Opened uartd. Adding fdMonitor”);
hApp->fdMonitorRef = le_fdMonitor_Create(“serial Comm”,
(le_fdMonitor_HandlerFunc_t) &AsyncRecvHandler,
LE_INFO(“uart open success”);
return hApp->serialFd;

void TimerVerHDLR(le_timer_Ref_t timerref)
uint8_t data={“uart write done”};
WriteToUart(data, sizeof(data) );


void CreateVerTimer(void)
le_timer_Ref_t timerRef;
le_clk_Time_t clk={ 60, 0};

timerRef = le_timer_Create(“send data”);
le_timer_SetHandler(timerRef ,TimerVerHDLR);

le_timer_SetInterval(timerRef ,clk);
le_timer_SetRepeat(timerRef ,0);


void createParseeventHdlr(void)
LE_INFO("%s", func);
hApp->CheckMsgEvtId = le_event_CreateId(“checkMsg”, sizeof(tm_Data_t));
hApp->CheckMsgEvtHdlr = le_event_AddHandler(“chaeckMsgHdlr”, hApp->CheckMsgEvtId, CheckMessageHdlr);


void* AppThreadHdlr (void* context)
if( OpenUart() < 0)
LE_INFO(“uart open fail”);


LE_INFO(“mcuData app start”);
le_thread_Ref_t ThreadRef;
ThreadRef = le_thread_Create(“mcuAPP”, AppThreadHdlr, NULL);

#ifndef MCUDATA_H
#define MCUDATA_H

#include “legato.h”
#include “interfaces.h”
#include <termios.h>
#include <unistd.h>

#define MCU_UART1 “/dev/ttyHS1”

#define BAUDRATE B460800
#define MAXRXLEN 256

#define PROT_STX 0x02
#define PROT_ETX 0x03
#define PROT_DLE 0x10

#define MSGTYPE_LEN 1
#define MSGLEN_LEN 2
#define MSGCRC_LEN 2

#define PRINTDATAINHEX(_msgstr ,_buf ,_maxLen) {int _offset=0, _i=0,_ret=0;
int _max= _maxLen;
uint8_t _ptr= _buf;
char _debugstr[50];
LE_INFO("%s: Len=%d", _msgstr ,_max);
while(_max >= _offset) {
memset(_debugstr, 0, sizeof(_debugstr) );
for(_i=0,_ret=0; _i<10 && _max >= _offset;_i++) {
_ret+= sprintf((char
)_debugstr+_ret, “%02x ,”, _ptr[_offset]);
_offset++; }
LE_INFO("%s: %s", _msgstr, _debugstr); }

typedef struct mcu
int serialFd; ///< Serial device file descriptor
char *PortName; ///<
le_fdMonitor_Ref_t fdMonitorRef; ///< Reference to the fd monitor

uint16_t RxLen;

uint8_t MessageBuf[MAXMCUDATALEN];
uint16_t MessageBufIndex;

bool bDLEFound;

le_event_Id_t CheckMsgEvtId;
le_event_HandlerRef_t CheckMsgEvtHdlr;

typedef struct buffer
uint16_t bLen;

int WriteToUart(const uint8_t *, uint32_t );




[rw] /dev/ttyHS1 /dev/ttyHS1

sandboxed: false
version: 1.0.0
start: auto


mcuData = ( mcuDataComponent )


( mcuData )
// faultAction: restartApp

Please zip it and put to google drive.

BTW, I don’t see problem on R10.1
mcudata.log (49.3 KB)

please find attached sample code file.

Hi jyijyi,

i tried in release 13.1 legato 19.02 fdmonitor is working in 1 millisec, but after i getting data from uart i need to send other application , so i created api event handler when we report this event handler event , again fdmonitor is hanging after few minute.
(NOTE:event handler registered function we are not doing any performance , suddenly i am returning from that function )

Do you have the reproducible steps for PC and mangoh red board?