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    Subject[PATCH] 8250: fix break handling for Intel 82571
    Intel 82571 has a "Serial Over LAN" feature that doesn't properly implements
    the receiving of break characters. When a break is received, it doesn't set
    UART_LSR_DR and unless another character is received, the break won't be
    received by the application.

    Signed-off-by: Aristeu Rozanski <arozansk@redhat.com>

    ---
    drivers/serial/8250.c | 17 ++++++++++++++---
    1 file changed, 14 insertions(+), 3 deletions(-)

    --- linus-2.6.orig/drivers/serial/8250.c 2008-05-15 13:32:48.000000000 -0400
    +++ linus-2.6/drivers/serial/8250.c 2008-05-15 13:48:59.000000000 -0400
    @@ -1296,7 +1296,18 @@ receive_chars(struct uart_8250_port *up,
    char flag;

    do {
    - ch = serial_inp(up, UART_RX);
    + if (likely(lsr & UART_LSR_DR))
    + ch = serial_inp(up, UART_RX);
    + else
    + /*
    + * Intel 82571 has a Serial Over Lan device that will
    + * set UART_LSR_BI without setting UART_LSR_DR when
    + * it receives a break. To avoid reading from the
    + * receive buffer without UART_LSR_DR bit set, we
    + * just force the read character to be 0
    + */
    + ch = 0;
    +
    flag = TTY_NORMAL;
    up->port.icount.rx++;

    @@ -1345,7 +1356,7 @@ receive_chars(struct uart_8250_port *up,

    ignore_char:
    lsr = serial_inp(up, UART_LSR);
    - } while ((lsr & UART_LSR_DR) && (max_count-- > 0));
    + } while ((lsr & (UART_LSR_DR | UART_LSR_BI)) && (max_count-- > 0));
    spin_unlock(&up->port.lock);
    tty_flip_buffer_push(tty);
    spin_lock(&up->port.lock);
    @@ -1428,7 +1439,7 @@ serial8250_handle_port(struct uart_8250_

    DEBUG_INTR("status = %x...", status);

    - if (status & UART_LSR_DR)
    + if (status & (UART_LSR_DR | UART_LSR_BI))
    receive_chars(up, &status);
    check_modem_status(up);
    if (status & UART_LSR_THRE)


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