From c557d392fbf5badd693ea1946a4317c87a26a716 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Sun, 6 Jul 2014 11:29:52 -0400 Subject: serial: Test for no tx data on tx restart Commit 717f3bbab3c7628736ef738fdbf3d9a28578c26c, 'serial_core: Fix conditional start_tx on ring buffer not empty' exposes an incorrect assumption in several drivers' start_tx methods; the tx ring buffer can, in fact, be empty when restarting tx while performing flow control. Affected drivers: sunsab.c ip22zilog.c pmac_zilog.c sunzilog.c m32r_sio.c imx.c Other in-tree serial drivers either are not affected or already test for empty tx ring buffer before transmitting. Test for empty tx ring buffer in start_tx() method, after transmitting x_char (if applicable). Reported-by: Aaro Koskinen Cc: Seth Bollinger Cc: "David S. Miller" Cc: Sam Ravnborg Cc: Thomas Bogendoerfer Signed-off-by: Peter Hurley Cc: stable # 3.15 Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/imx.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers/tty/serial/imx.c') diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index e2f93874989b..56bd9aa56151 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -567,6 +567,9 @@ static void imx_start_tx(struct uart_port *port) struct imx_port *sport = (struct imx_port *)port; unsigned long temp; + if (uart_circ_empty(&port.state->xmit)) + return; + if (USE_IRDA(sport)) { /* half duplex in IrDA mode; have to disable receive mode */ temp = readl(sport->port.membase + UCR4); -- cgit