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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>
This commit is contained in:
Jakub Kicinski 2015-05-29 21:20:28 +02:00 committed by Greg Kroah-Hartman
parent 4117a60c8e
commit 4ae82e5d23
1 changed files with 2 additions and 3 deletions
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5
drivers/tty/serial/sc16is7xx.c
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@ -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)