I can't read data from COM1

Green Mon, 09 Apr 2001 13:43:08 -0700

Hi all,

I write a sample code(user mode) to test the serial driver.

I can open COM1 and write string to COM1.

But, when I want to read data from COM1, the program will block at read function.

I trace the driver source code.

When the program execute write operation, it will call tty_write( ) at /drivers/char/tty_io.c.

Then it will call gs_write( ) at /drivers/char/general.c.

When the program execute read operation,it will call tty_read( ) at /drivers/char/tty_io.c.

Then I don't know which function would be called.

But it was blocked at operation which called (tty->ldisc.read)(tty,file,buf,count), as the following

/* Function tty_read( ) in tty_io.c */

if (tty->ldisc.read)
{
      /* Program will be blocked here */
      i = (tty->ldisc.read)(tty,file,buf,count);
}
else
{
      /* Error happened */
      i = -EIO;
}

What parameter should I reset?

Thanks in advance.

Green

I can't read data from COM1

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