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    Subject[PATCH 04/14] serial: tegra: protect IER against LCR.DLAB
    Date
    From: Ahung Cheng <ahcheng@nvidia.com>

    The IER and DLH registers occupy the same address space, selected by
    the LCR.DLAB bit. Hence, add port lock to protect IER when LCR.DLAB bit
    is set.

    Signed-off-by: Ahung Cheng <ahcheng@nvidia.com>
    Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com>
    ---
    drivers/tty/serial/serial-tegra.c | 3 +++
    1 file changed, 3 insertions(+)

    diff --git a/drivers/tty/serial/serial-tegra.c b/drivers/tty/serial/serial-tegra.c
    index d908465..ae7225c 100644
    --- a/drivers/tty/serial/serial-tegra.c
    +++ b/drivers/tty/serial/serial-tegra.c
    @@ -296,6 +296,7 @@ static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned int baud)
    unsigned long rate;
    unsigned int divisor;
    unsigned long lcr;
    + unsigned long flags;
    int ret;

    if (tup->current_baud == baud)
    @@ -315,6 +316,7 @@ static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned int baud)
    divisor = DIV_ROUND_CLOSEST(rate, baud * 16);
    }

    + spin_lock_irqsave(&tup->uport.lock, flags);
    lcr = tup->lcr_shadow;
    lcr |= UART_LCR_DLAB;
    tegra_uart_write(tup, lcr, UART_LCR);
    @@ -327,6 +329,7 @@ static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned int baud)

    /* Dummy read to ensure the write is posted */
    tegra_uart_read(tup, UART_SCR);
    + spin_unlock_irqrestore(&tup->uport.lock, flags);

    tup->current_baud = baud;

    --
    2.7.4
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