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    Subject[PATCH 3.12 66/98] 8250: use callbacks to access UART_DLL/UART_DLM
    Date
    From: Sebastian Frias <sf84@laposte.net>

    3.12-stable review patch. If anyone has any objections, please let me know.

    ===============

    commit 0b41ce991052022c030fd868e03877700220b090 upstream.

    Some UART HW has a single register combining UART_DLL/UART_DLM
    (this was probably forgotten in the change that introduced the
    callbacks, commit b32b19b8ffc05cbd3bf91c65e205f6a912ca15d9)

    Fixes: b32b19b8ffc0 ("[SERIAL] 8250: set divisor register correctly ...")

    Signed-off-by: Sebastian Frias <sf84@laposte.net>
    Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
    Signed-off-by: Jiri Slaby <jslaby@suse.cz>
    ---
    drivers/tty/serial/8250/8250_core.c | 18 ++++++------------
    1 file changed, 6 insertions(+), 12 deletions(-)

    diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
    index 04c8772639d3..a9eb91c51884 100644
    --- a/drivers/tty/serial/8250/8250_core.c
    +++ b/drivers/tty/serial/8250/8250_core.c
    @@ -686,22 +686,16 @@ static int size_fifo(struct uart_8250_port *up)
    */
    static unsigned int autoconfig_read_divisor_id(struct uart_8250_port *p)
    {
    - unsigned char old_dll, old_dlm, old_lcr;
    - unsigned int id;
    + unsigned char old_lcr;
    + unsigned int id, old_dl;

    old_lcr = serial_in(p, UART_LCR);
    serial_out(p, UART_LCR, UART_LCR_CONF_MODE_A);
    + old_dl = serial_dl_read(p);
    + serial_dl_write(p, 0);
    + id = serial_dl_read(p);
    + serial_dl_write(p, old_dl);

    - old_dll = serial_in(p, UART_DLL);
    - old_dlm = serial_in(p, UART_DLM);
    -
    - serial_out(p, UART_DLL, 0);
    - serial_out(p, UART_DLM, 0);
    -
    - id = serial_in(p, UART_DLL) | serial_in(p, UART_DLM) << 8;
    -
    - serial_out(p, UART_DLL, old_dll);
    - serial_out(p, UART_DLM, old_dlm);
    serial_out(p, UART_LCR, old_lcr);

    return id;
    --
    2.8.1
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