svn commit: r338809 - stable/10/sys/dev/uart

[Alexander Motin]

Author: mav
Date: Wed Sep 19 19:54:13 2018
New Revision: 338809
URL: https://svnweb.freebsd.org/changeset/base/338809

Log:
  MFC r317659, r317752:
  Make some UART consoles to not spin wait for data to be sent.
  
  At least with Tx FIFO enabled it shows me ~10% reduction of verbose boot
  time with serial console at 115200 baud.

Modified:
  stable/10/sys/dev/uart/uart_dev_lpc.c
  stable/10/sys/dev/uart/uart_dev_ns8250.c
Directory Properties:
  stable/10/   (props changed)

Modified: stable/10/sys/dev/uart/uart_dev_lpc.c
==============================================================================
--- stable/10/sys/dev/uart/uart_dev_lpc.c	Wed Sep 19 19:52:53 2018	(r338808)
+++ stable/10/sys/dev/uart/uart_dev_lpc.c	Wed Sep 19 19:54:13 2018	(r338809)
@@ -346,9 +346,6 @@ lpc_ns8250_putc(struct uart_bas *bas, int c)
 		DELAY(4);
 	uart_setreg(bas, REG_DATA, c);
 	uart_barrier(bas);
-	limit = 250000;
-	while ((uart_getreg(bas, REG_LSR) & LSR_TEMT) == 0 && --limit)
-		DELAY(4);
 }
 
 static int
@@ -889,8 +886,13 @@ lpc_ns8250_bus_transmit(struct uart_softc *sc)
 
 	bas = &sc->sc_bas;
 	uart_lock(sc->sc_hwmtx);
-	while ((uart_getreg(bas, REG_LSR) & LSR_THRE) == 0)
-		;
+	if (sc->sc_txdatasz > 1) {
+		if ((uart_getreg(bas, REG_LSR) & LSR_TEMT) == 0)
+			lpc_ns8250_drain(bas, UART_DRAIN_TRANSMITTER);
+	} else {
+		while ((uart_getreg(bas, REG_LSR) & LSR_THRE) == 0)
+			DELAY(4);
+	}
 	uart_setreg(bas, REG_IER, lpc_ns8250->ier | IER_ETXRDY);
 	uart_barrier(bas);
 	for (i = 0; i < sc->sc_txdatasz; i++) {

Modified: stable/10/sys/dev/uart/uart_dev_ns8250.c
==============================================================================
--- stable/10/sys/dev/uart/uart_dev_ns8250.c	Wed Sep 19 19:52:53 2018	(r338808)
+++ stable/10/sys/dev/uart/uart_dev_ns8250.c	Wed Sep 19 19:54:13 2018	(r338809)
@@ -305,7 +305,7 @@ ns8250_init(struct uart_bas *bas, int baudrate, int da
 	/* Disable the FIFO (if present). */
 	val = 0;
 #ifdef CPU_XBURST
-	val = FCR_UART_ON;
+	val |= FCR_UART_ON;
 #endif
 	uart_setreg(bas, REG_FCR, val);
 	uart_barrier(bas);
@@ -336,9 +336,6 @@ ns8250_putc(struct uart_bas *bas, int c)
 		DELAY(4);
 	uart_setreg(bas, REG_DATA, c);
 	uart_barrier(bas);
-	limit = 250000;
-	while ((uart_getreg(bas, REG_LSR) & LSR_TEMT) == 0 && --limit)
-		DELAY(4);
 }
 
 static int
@@ -993,8 +990,13 @@ ns8250_bus_transmit(struct uart_softc *sc)
 
 	bas = &sc->sc_bas;
 	uart_lock(sc->sc_hwmtx);
-	while ((uart_getreg(bas, REG_LSR) & LSR_THRE) == 0)
-		;
+	if (sc->sc_txdatasz > 1) {
+		if ((uart_getreg(bas, REG_LSR) & LSR_TEMT) == 0)
+			ns8250_drain(bas, UART_DRAIN_TRANSMITTER);
+	} else {
+		while ((uart_getreg(bas, REG_LSR) & LSR_THRE) == 0)
+			DELAY(4);
+	}
 	uart_setreg(bas, REG_IER, ns8250->ier | IER_ETXRDY);
 	uart_barrier(bas);
 	for (i = 0; i < sc->sc_txdatasz; i++) {