Commit 44763d3d authored Jun 24, 2016 by Geert Uytterhoeven Committed by Greg Kroah-Hartman Jun 25, 2016

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



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>

parent ac8305cd

drivers/tty/serial/sh-sci.c

+0 −6

Original line number	Diff line number	Diff line
		@@ -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;
		}