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    Subject[PATCH 02/25] serial: bfin_sport_uart: shorten the SPORT TX waiting loop
    Date
    From: Sonic Zhang <sonic.zhang@analog.com>

    The waiting loop to stop SPORT TX from TX interrupt is too long. This may
    block the SPORT RX interrupts and cause the RX FIFO to overflow. So, do
    stop sport TX only after the last char in TX FIFO is moved into the shift
    register.

    Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
    Signed-off-by: Mike Frysinger <vapier@gentoo.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
    ---
    drivers/serial/bfin_sport_uart.c | 8 +++++++-
    1 files changed, 7 insertions(+), 1 deletions(-)

    diff --git a/drivers/serial/bfin_sport_uart.c b/drivers/serial/bfin_sport_uart.c
    index c88f8ad..6991c36 100644
    --- a/drivers/serial/bfin_sport_uart.c
    +++ b/drivers/serial/bfin_sport_uart.c
    @@ -271,7 +271,13 @@ static void sport_uart_tx_chars(struct sport_uart_port *up)
    }

    if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
    - sport_stop_tx(&up->port);
    + /* The waiting loop to stop SPORT TX from TX interrupt is
    + * too long. This may block SPORT RX interrupts and cause
    + * RX FIFO overflow. So, do stop sport TX only after the last
    + * char in TX FIFO is moved into the shift register.
    + */
    + if (SPORT_GET_STAT(up) & TXHRE)
    + sport_stop_tx(&up->port);
    return;
    }

    --
    1.7.0.3


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