serial: 8250: Return early in .start_tx() if there are no chars to send

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Don't start the whole chain for TX if there is no data to send. This is
mostly relevant for rs485 mode as there might be rts-before-send and
rts-after-send delays involved.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20220217211839.443039-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Steffen Trumtrar 2022-02-17 22:18:39 +01:00 • committed by Greg Kroah-Hartman

parent 52fa786609

commit 932d596378

1 changed files with 3 additions and 0 deletions

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drivers/tty/serial/8250/8250_port.c

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