Yes Greg, absolutely. It has no problem working without two threads. I can
write a HCI reset packet and I get correct response from the subsequent
read. I was wondering if at all I need look at the flip-buffer of tty layer
when debugging the issue with read when the read part is handled in a
different thread. Because once a seperate thread starts handling read, with
termios settings VMIN = 1 the read never returns at all and when VMIN=0
read returns, but with zero bytes read. I have again appended my original
mail with the code stub for easy reference below. What might be the problem,
any ideas ?
Thanks
amol
>2004-08-12 15:41, Greg KH wrote :
>I really don't know, sorry. Odds are it's a syncronization issue.
> Does it work without 2 threads?
>
>thanks,
>greg k-h
>On Thu, Aug 12, 2004 at 06:30:04PM +0530, Amol Kailash wrote:
> Hi Greg,
> I have a bluetooth stack as a shared object. While starting
> the stack I initiate a pthread to read from the tty driver in a loop. The
main thread meanwhile sends a HCI reset packet to the tty driver using the
write function as shown in the code stub below. Now my problem is when the
dcb->c_cc[VMIN] = 1, the read function never returns at all, even after I
added synchornization so that the first read executes only after the
usb_write function writes a reset packet. So I set dcb->c_cc[VMIN] = 0, now
read returns alright, but never returns a single byte. Will it have
something to do with the bluetooth tty driver and some issues with the tty
buffer that it uses or would it be some sort of a timing problem with the
read thread syncronization ? And how can I go about solving this ?
-----------------------------------------------------Code------------------
-
--------------------------
HANDLE cardHandle =NULL;
main(){
usb_connect(...);
usb_write(...);
}
usb_connect(...){
termios *dcb =NULL;
if ((cardHandle = open("/dev/ttyUB0", O_RDWR | O_NOCTTY | O_NDELAY)) == -1)
goto error;
fcntl(g_btsInfo.cardHandle,F_SETFL,0);
tcgetattr(g_btsInfo.cardHandle,dcb);
cfsetispeed(dcb,B57600);
cfsetospeed(dcb,B57600);
dcb->c_cflag &=~PARENB;
dcb->c_cflag &=~CSTOPB;
dcb->c_cflag &=~CSIZE;
dcb->c_cflag |=CS8;
dcb->c_cflag |=CRTSCTS;
dcb->c_cflag |=CLOCAL |CREAD;
dcb->c_lflag = 0; // enable non canonical input with no echo
dcb->c_oflag=0;
dcb->c_iflag&=~(IXON | IXOFF | IXANY);
dcb->c_iflag |=IGNPAR;
dcb->c_cc[VMIN] = 1; // returns when there is 1 byte in
buffer
tcflush(cardHandle, TCIFLUSH);
tcsetattr(cardHandle,TCSANOW,dcb);
pthread_create( &thread_id, NULL, readThread, NULL);
}
readThread(){
while(threadNotStopped){
nbytes = read(cardHandle, readBuf, count);
}
}
usb_write(....){
nbytes = write(cardHandle, writeBuf, count);
}
Thanks
regards
amol
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