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    SubjectRe: Locking in the clk API
    On Wed, Jan 26, 2011 at 08:34:20PM -0800, Saravana Kannan wrote:
    > I'm not too familiar with serial/tty, does anyone know if the
    > .set_termios needs to be atmoic? If not, we could just change
    > cpm_uart/cpm_uart_core.c to use mutex instead of spinlock.

    The locking is there to protect against the interrupt handler accessing
    the port->* stuff (which seems to have been forgotten by the cpm driver).

    I don't see any reason why clk_set_rate() needs to be under the spinlock
    there - we need the reprogramming of the baud rate within the spinlock
    on 8250 because of DLAB bit hiding the data registers. It's also a good
    idea that it _is_ within the spinlock along with uart_update_timeout()
    to ensure timeouts and the baud rate are updated together.

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