diff -Naur linux-2.2.14/Documentation/Configure.help linux-2.2.14-NecDuart/Documentation/Configure.help
--- linux-2.2.14/Documentation/Configure.help	Tue Apr 25 16:21:15 2000
+++ linux-2.2.14-NecDuart/Documentation/Configure.help	Sun Dec 10 13:39:52 2000
@@ -1343,6 +1343,20 @@
 
   Most people can say N here.
 
+Bugfix for NEC NS16C55x UARTs
+CONFIG_NEC_DUART_SUPPORT
+  Say Y here if you have a NEC NS1655x-family UART (NS16550Ax,
+  NS16C552x), and are experiencing problems (characters loss).
+  The standard serial driver is used to confuse the NEC UARTs
+  with Startech UARTs without FIFO support (NEC UARTs have
+  full 16550A FIFO). Use the "setserial" command to know if the
+  kernel has detected the wrong chip model.
+
+  You must say Y also if you are using the SER2 or IOSPC64 cards
+  produced by CNi (www.cnisrl.it).
+
+  If unsure, say N.
+
 Extended dumb serial driver options
 CONFIG_SERIAL_EXTENDED
   If you wish to use any non-standard features of the standard "dumb"
diff -Naur linux-2.2.14/drivers/char/Config.in linux-2.2.14-NecDuart/drivers/char/Config.in
--- linux-2.2.14/drivers/char/Config.in	Tue Apr 25 16:21:14 2000
+++ linux-2.2.14-NecDuart/drivers/char/Config.in	Sun Dec 10 13:35:29 2000
@@ -10,6 +10,7 @@
 fi
 tristate 'Standard/generic (dumb) serial support' CONFIG_SERIAL
 if [ "$CONFIG_SERIAL" = "y" ]; then
+   bool '   Bugfix for NEC UARTs (NS16C55x)' CONFIG_NEC_DUART_SUPPORT
    bool '   Support for console on serial port' CONFIG_SERIAL_CONSOLE
 fi
 bool 'Extended dumb serial driver options' CONFIG_SERIAL_EXTENDED
diff -Naur linux-2.2.14/drivers/char/serial.c linux-2.2.14-NecDuart/drivers/char/serial.c
--- linux-2.2.14/drivers/char/serial.c	Tue Apr 25 16:21:13 2000
+++ linux-2.2.14-NecDuart/drivers/char/serial.c	Sun Dec 10 13:43:17 2000
@@ -154,8 +154,13 @@
 #define _INLINE_ inline
 #endif
 	
+
 static char *serial_name = "Serial driver";
-static char *serial_version = "4.27";
+static char *serial_version = "4.27"
+#ifdef CONFIG_NEC_DUART_SUPPORT
+	" - NECDUART fix 1.0"
+#endif
+					;
 
 static DECLARE_TASK_QUEUE(tq_serial);
 
@@ -199,6 +204,18 @@
 	{ "ST16650V2", 32, UART_CLEAR_FIFO | UART_USE_FIFO |
 		  UART_STARTECH }, 
 	{ "TI16750", 64, UART_CLEAR_FIFO | UART_USE_FIFO},
+#ifdef CONFIG_NEC_DUART_SUPPORT
+	  /* The NEC NS16C55x is actually a 16550A. If I added
+	   * a specific record for this particular chipset in "uart_config",
+	   * I would have to change both "serial.h" and the "setserial"
+	   * utility. I don't think it's worth. Anyway, this source is
+	   * ready to accept the change. */
+#ifndef PORT_NS16C550AF
+#define PORT_NS16C550AF (PORT_MAX + 1)
+#else
+	{ "NS16C55x", 16, UART_CLEAR_FIFO | UART_USE_FIFO }, 
+#endif
+#endif
 	{ 0, 0}
 };
 
@@ -2821,6 +2838,10 @@
 static _INLINE_ void show_serial_version(void)
 {
  	printk(KERN_INFO "%s version %s with", serial_name, serial_version);
+#ifdef CONFIG_NEC_DUART_SUPPORT
+	printk(" NEC_DUART");
+#define SERIAL_OPT
+#endif
 #ifdef CONFIG_HUB6
 	printk(" HUB-6");
 #define SERIAL_OPT
@@ -2959,8 +2980,8 @@
 	scratch2 = serial_inp(info, UART_IER);
 	serial_outp(info, UART_IER, scratch);
 	if (scratch2) {
-		restore_flags(flags);
-		return;		/* We failed; there's nothing here */
+		/* We failed; there's nothing here */
+		goto autoconfig_END_fail;
 	}
 
 	/* 
@@ -2979,8 +3000,7 @@
 		status1 = serial_inp(info, UART_MSR) & 0xF0;
 		serial_outp(info, UART_MCR, scratch);
 		if (status1 != 0x90) {
-			restore_flags(flags);
-			return;
+			goto autoconfig_END_fail;
 		}
 	} 
 	
@@ -3008,13 +3028,61 @@
 		/* Check for Startech UART's */
 		serial_outp(info, UART_LCR, scratch2 | UART_LCR_DLAB);
 		if (serial_in(info, UART_EFR) == 0) {
+#ifdef CONFIG_NEC_DUART_SUPPORT
+		  /* giusguerrini@racine.ra.it: Both ST16650 and NS16C55x
+		   * behaves the same, so the ortiginal algorithm is not
+		   * enough to detect them. We have to do something
+		   * smarter. */
+		  /* OK, there could be an ST16650 or a NEC NS16C55x.
+		   * The former uses many bits in EFR(=FCR+DLAB), the latter
+		   * uses only bits 0, 1 and 2, and zeroes other bits.
+		   * So, we'll try to detect an ST16650 by setting some
+		   * high bit in EFR (e.g. the CTS protocol enabler), and
+		   * then verifying if it has really been set. */
+			serial_outp(info, UART_LCR, 0xBF);
+			serial_outp(info, UART_EFR, UART_EFR_CTS);
+			serial_outp(info, UART_LCR, 0xBF);
+			if (serial_in(info, UART_EFR) & UART_EFR_CTS) {
+			  /* bit set succeeded. It's an ST16650. */
+				state->type = PORT_16650;
+				serial_outp(info, UART_LCR, 0xBF);
+				serial_outp(info, UART_EFR, 0);
+			}
+			else {
+			  /* bit set unsuccesful. Perhaps we are using a NEC double UART.
+			   * We must remeber it, because
+			   *  - this chip fully supports the 166550A mode,
+			   *  - this chip doesn't like the TI 16750
+			   *    detection algorithm, so we must avoid it. */
+				state->type = PORT_NS16C550AF;
+				serial_outp(info, UART_LCR, scratch2);
+			}
+#else /* CONFIG_NEC_DUART_SUPPORT */
 			state->type = PORT_16650;
+#endif /* CONFIG_NEC_DUART_SUPPORT */
 		} else {
 			serial_outp(info, UART_LCR, 0xBF);
 			if (serial_in(info, UART_EFR) == 0)
 				state->type = PORT_16650V2;
 		}
 	}
+#ifdef CONFIG_NEC_DUART_SUPPORT
+	if (state->type == PORT_NS16C550AF) {
+#if PORT_NS16C550AF == (PORT_MAX + 1)
+	  /* Hide the "internal" type code. I'm too lazy to change
+	   * serail.h, setserial,... But the code is ready. */
+		state->type = PORT_16550A;
+#endif
+		serial_outp(info, UART_FCR, UART_FCR_ENABLE_FIFO);
+	}
+	else
+	/* giusguerrini@racine.ra.it: Arrrgh! This messes up the NEC
+	 * NS16C552A dual UART. Bit 0 of FCR+DLAB enables concurrent write
+	 * on registers of BOTH UARTs. So, with this chip we can't write
+	 * the ENABLE_FIFO bit when DLAB is set. That's why we won't
+	 * execute this code if we detected a NS16C55x (and, anyway,
+	 * we have already detected the chip!). */
+#endif /* CONFIG_NEC_DUART_SUPPORT */
 	if (state->type == PORT_16550A) {
 		/* Check for TI 16750 */
 		serial_outp(info, UART_LCR, scratch2 | UART_LCR_DLAB);
@@ -3044,8 +3112,7 @@
 	state->xmit_fifo_size =	uart_config[state->type].dfl_xmit_fifo_size;
 
 	if (state->type == PORT_UNKNOWN) {
-		restore_flags(flags);
-		return;
+		goto autoconfig_END_fail;
 	}
 
 	request_region(info->port,8,"serial(auto)");
@@ -3066,8 +3133,13 @@
 				     UART_FCR_CLEAR_XMIT));
 	(void)serial_in(info, UART_RX);
 	serial_outp(info, UART_IER, 0);
-	
+
+autoconfig_END:
 	restore_flags(flags);
+	return;
+
+autoconfig_END_fail:
+	goto autoconfig_END;
 }
 
 int register_serial(struct serial_struct *req);