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Date:      Fri, 12 Feb 2016 05:14:58 +0000 (UTC)
From:      Michal Meloun <mmel@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r295557 - head/sys/dev/uart
Message-ID:  <201602120514.u1C5EwWt053622@repo.freebsd.org>
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Author: mmel
Date: Fri Feb 12 05:14:58 2016
New Revision: 295557
URL: https://svnweb.freebsd.org/changeset/base/295557

Log:
  UART: Fix spurious interrupts generated by ns8250 and lpc drivers:
   - don't enable transmitter empty interrupt before filling TX FIFO.
   - add missing uart_barrier() call in interrupt service routine

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	Fri Feb 12 02:53:44 2016	(r295556)
+++ head/sys/dev/uart/uart_dev_lpc.c	Fri Feb 12 05:14:58 2016	(r295557)
@@ -659,6 +659,7 @@ lpc_ns8250_bus_ipend(struct uart_softc *
 		if (iir & IIR_TXRDY) {
 			ipend |= SER_INT_TXIDLE;
 			uart_setreg(bas, REG_IER, lpc_ns8250->ier);
+			uart_barrier(bas);
 		} else
 			ipend |= SER_INT_SIGCHG;
 	}
@@ -892,12 +893,12 @@ lpc_ns8250_bus_transmit(struct uart_soft
 	uart_lock(sc->sc_hwmtx);
 	while ((uart_getreg(bas, REG_LSR) & LSR_THRE) == 0)
 		;
-	uart_setreg(bas, REG_IER, lpc_ns8250->ier | IER_ETXRDY);
-	uart_barrier(bas);
 	for (i = 0; i < sc->sc_txdatasz; i++) {
 		uart_setreg(bas, REG_DATA, sc->sc_txbuf[i]);
 		uart_barrier(bas);
 	}
+	uart_setreg(bas, REG_IER, lpc_ns8250->ier | IER_ETXRDY);
+	uart_barrier(bas);
 	sc->sc_txbusy = 1;
 	uart_unlock(sc->sc_hwmtx);
 	return (0);

Modified: head/sys/dev/uart/uart_dev_ns8250.c
==============================================================================
--- head/sys/dev/uart/uart_dev_ns8250.c	Fri Feb 12 02:53:44 2016	(r295556)
+++ head/sys/dev/uart/uart_dev_ns8250.c	Fri Feb 12 05:14:58 2016	(r295557)
@@ -708,6 +708,7 @@ ns8250_bus_ipend(struct uart_softc *sc)
 		if (iir & IIR_TXRDY) {
 			ipend |= SER_INT_TXIDLE;
 			uart_setreg(bas, REG_IER, ns8250->ier);
+			uart_barrier(bas);
 		} else
 			ipend |= SER_INT_SIGCHG;
 	}
@@ -979,12 +980,12 @@ ns8250_bus_transmit(struct uart_softc *s
 	uart_lock(sc->sc_hwmtx);
 	while ((uart_getreg(bas, REG_LSR) & LSR_THRE) == 0)
 		;
-	uart_setreg(bas, REG_IER, ns8250->ier | IER_ETXRDY);
-	uart_barrier(bas);
 	for (i = 0; i < sc->sc_txdatasz; i++) {
 		uart_setreg(bas, REG_DATA, sc->sc_txbuf[i]);
 		uart_barrier(bas);
 	}
+	uart_setreg(bas, REG_IER, ns8250->ier | IER_ETXRDY);
+	uart_barrier(bas);
 	if (broken_txfifo)
 		ns8250_drain(bas, UART_DRAIN_TRANSMITTER);
 	else

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