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serial: sh-sci: Do not start transfers from sci_startup()

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FIFO reset is done in sci_reset(), called from sci_set_termios(), while
sci_start_tx() and sci_start_rx() are called before, from sci_startup().
However, starting transfers before the UART's FIFOs have been reset may
cause reading of stale data.

Remove the calls to sci_start_tx() and sci_start_rx() from sci_startup()
to fix this.

Transfers are still started when needed:
  - sci_start_rx() is called from sci_set_termios() after FIFO reset, if
    the CREAD flag is set,
  - sci_start_tx() is called from uart_change_speed() immediately
    thereafter, if transmission is enabled.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Geert Uytterhoeven 2016-06-24 16:59:13 +02:00 committed by Greg Kroah-Hartman
parent ac8305cd16
commit 44763d3d30
1 changed files with 0 additions and 6 deletions
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6
drivers/tty/serial/sh-sci.c
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@ -1972,7 +1972,6 @@ static void sci_break_ctl(struct uart_port *port, int break_state)
static int sci_startup(struct uart_port *port)
{
struct sci_port *s = to_sci_port(port);
unsigned long flags;
int ret;
dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);
@ -1983,11 +1982,6 @@ static int sci_startup(struct uart_port *port)
sci_request_dma(port);
spin_lock_irqsave(&port->lock, flags);
sci_start_tx(port);
sci_start_rx(port);
spin_unlock_irqrestore(&port->lock, flags);
return 0;
}