svn commit: r317659 - head/sys/dev/uart

[Alexander Motin]

Author: mav
Date: Mon May  1 19:47:10 2017
New Revision: 317659
URL: https://svnweb.freebsd.org/changeset/base/317659

Log:
  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.
  
  Reviewed by:  marcel
  MFC after:    2 weeks

Modified:
  head/sys/dev/uart/uart_dev_lpc.c
  head/sys/dev/uart/uart_dev_ns8250.c

Modified: head/sys/dev/uart/uart_dev_lpc.c
==============================================================================
--- head/sys/dev/uart/uart_dev_lpc.c    Mon May  1 19:34:15 2017        
(r317658)
+++ head/sys/dev/uart/uart_dev_lpc.c    Mon May  1 19:47:10 2017        
(r317659)
@@ -345,9 +345,6 @@ lpc_ns8250_putc(struct uart_bas *bas, in
                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
@@ -890,8 +887,13 @@ lpc_ns8250_bus_transmit(struct uart_soft
 
        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);
+       }
        for (i = 0; i < sc->sc_txdatasz; i++) {
                uart_setreg(bas, REG_DATA, sc->sc_txbuf[i]);
                uart_barrier(bas);

Modified: head/sys/dev/uart/uart_dev_ns8250.c
==============================================================================
--- head/sys/dev/uart/uart_dev_ns8250.c Mon May  1 19:34:15 2017        
(r317658)
+++ head/sys/dev/uart/uart_dev_ns8250.c Mon May  1 19:47:10 2017        
(r317659)
@@ -315,7 +315,7 @@ ns8250_init(struct uart_bas *bas, int ba
        /* 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);
@@ -346,9 +346,6 @@ 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
@@ -999,8 +996,13 @@ ns8250_bus_transmit(struct uart_softc *s
 
        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);
+       }
        for (i = 0; i < sc->sc_txdatasz; i++) {
                uart_setreg(bas, REG_DATA, sc->sc_txbuf[i]);
                uart_barrier(bas);
_______________________________________________
svn-src-all@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"