sc16is7xx: use LSR_TEMT_BIT in .tx_empty()

LSR_TEMT_BIT (LSR bit 6) provides us exactly the information
we need to determine if transmission is finished - FIFO level
and shift register empty.  We can save ourselves reading FIFO
level explicitly if we use this bit.

Signed-off-by: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 0509be0..ea61a29 100644 (file)
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -683,12 +683,11 @@ static void sc16is7xx_start_tx(struct uart_port *port)
 
 static unsigned int sc16is7xx_tx_empty(struct uart_port *port)
 {
-       unsigned int lvl, lsr;
+       unsigned int lsr;
 
-       lvl = sc16is7xx_port_read(port, SC16IS7XX_TXLVL_REG);
        lsr = sc16is7xx_port_read(port, SC16IS7XX_LSR_REG);
 
-       return ((lsr & SC16IS7XX_LSR_THRE_BIT) && !lvl) ? TIOCSER_TEMT : 0;
+       return (lsr & SC16IS7XX_LSR_TEMT_BIT) ? TIOCSER_TEMT : 0;
 }
 
 static unsigned int sc16is7xx_get_mctrl(struct uart_port *port)