serial: imx: Fix x_char handling and tx flow control

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The serial core expects the UART driver to transmit x_char
(START/STOP chars) even if tx is stopped and before data already
in the tx ring buffer if possible. Also, sending x_char must
not cause additional data in the tx ring buffer to transmit
if tx is stopped.

Cause x_char to be transmitted before any other data is sent.
Auto-stop tx if the tx ring buffer is empty or tx should be stopped.
Only perform one write wakeup if tx ring buffer space is below
threshold.

x_char handling in DMA mode is still broken; add FIXME.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Peter Hurley 2014-09-02 17:39:12 -04:00 • committed by Greg Kroah-Hartman

parent 99abf3b924

commit 5e42e9a30c

1 changed files with 16 additions and 23 deletions

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39

drivers/tty/serial/imx.c

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