serial: imx: implement the flush_buffer hook

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The current driver does not implement the flush_buffer hook for
uart_ops. When we enable the DMA for the driver, and test it with Bluetooth,
we may meet the following bug for TX:

    [1] User application may call the flush operation at any time.
        The uart_flush_buffer() calls the uart_circ_clear() to set
        the xmit->head and xmit->tail with 0.

    [2] The TX DMA callback can be called at any time too.
        The dma_tx_call() will update the xmit->tail.

    If [2] occurs just after the [1], we will get the wrong xmit->tail.

This patch implements the flush_buffer hook to fix this issue.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Huang Shijie 2013-10-11 18:30:58 +08:00 • committed by Greg Kroah-Hartman

parent fa2b5ea09e

commit eb56b7edae

1 changed files with 11 additions and 0 deletions

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drivers/tty/serial/imx.c

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