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serial: timbuart: make sure last byte is sent when port is closed 

Fix a problem in early versions of the FPGA IP.

In certain situations the IP reports that the FIFO is empty, but a byte is
still clocked out.  If a flush is done at that point the currently clocked
byte is canceled.

This causes incompatibilities with the upper layers when a port is closed,
it waits until the FIFO is empty and then closes the port.  During close
the FIFO is flushed -> the last byte is not sent properly.

Now the FIFO is only flushed if it is reported to be non-empty.  Which
makes the currently clocked out byte to finish.

[akpm@linux-foundation.org: fix build]
Signed-off-by: Richard Röjfors <richard.rojfors@pelagicore.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
hifive-unleashed-5.1
Richard Röjfors 2010-04-27 14:16:34 -07:00 committed by Greg Kroah-Hartman
parent 4405199623
commit 24cd73a394
1 changed files with 13 additions and 10 deletions
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23
drivers/serial/timbuart.c
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@ -68,12 +68,22 @@ static void timbuart_start_tx(struct uart_port *port)
tasklet_schedule(&uart->tasklet);
}
static unsigned int timbuart_tx_empty(struct uart_port *port)
{
u32 isr = ioread32(port->membase + TIMBUART_ISR);
return (isr & TXBE) ? TIOCSER_TEMT : 0;
}
static void timbuart_flush_buffer(struct uart_port *port)
{
u8 ctl = ioread8(port->membase + TIMBUART_CTRL) | TIMBUART_CTRL_FLSHTX;
if (!timbuart_tx_empty(port)) {
u8 ctl = ioread8(port->membase + TIMBUART_CTRL) |
TIMBUART_CTRL_FLSHTX;
iowrite8(ctl, port->membase + TIMBUART_CTRL);
iowrite32(TXBF, port->membase + TIMBUART_ISR);
iowrite8(ctl, port->membase + TIMBUART_CTRL);
iowrite32(TXBF, port->membase + TIMBUART_ISR);
}
}
static void timbuart_rx_chars(struct uart_port *port)
@ -195,13 +205,6 @@ void timbuart_tasklet(unsigned long arg)
dev_dbg(uart->port.dev, "%s leaving\n", __func__);
}
static unsigned int timbuart_tx_empty(struct uart_port *port)
{
u32 isr = ioread32(port->membase + TIMBUART_ISR);
return (isr & TXBE) ? TIOCSER_TEMT : 0;
}
static unsigned int timbuart_get_mctrl(struct uart_port *port)
{
u8 cts = ioread8(port->membase + TIMBUART_CTRL);