Date: Wed, 19 Sep 2018 19:54:13 +0000 (UTC) From: Alexander Motin <mav@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r338809 - stable/10/sys/dev/uart Message-ID: <201809191954.w8JJsDh0064819@repo.freebsd.org>
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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++) {
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