[PATCH 6.8 614/715] tty: serial: samsung: fix tx_empty() to return TIOCSER_TEMT

Sasha Levin
2024-03-24T22:45:06Z

From: Tudor Ambarus <tudor.ambarus@linaro.org>

[ Upstream commit 314c2b399288f0058a8c5b6683292cbde5f1531b ]

The core expects for tx_empty() either TIOCSER_TEMT when the tx is
empty or 0 otherwise. s3c24xx_serial_txempty_nofifo() might return
0x4, and at least uart_get_lsr_info() tries to clear exactly
TIOCSER_TEMT (BIT(1)). Fix tx_empty() to return TIOCSER_TEMT.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20240119104526.1221243-2-tudor.ambarus@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/samsung_tty.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index 71d17d804fdab..6fdb32b833466 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -987,11 +987,10 @@ static unsigned int s3c24xx_serial_tx_empty(struct uart_port *port)
if ((ufstat & info->tx_fifomask) != 0 ||
(ufstat & info->tx_fifofull))
return 0;
-
- return 1;
+ return TIOCSER_TEMT;
}

- return s3c24xx_serial_txempty_nofifo(port);
+ return s3c24xx_serial_txempty_nofifo(port) ? TIOCSER_TEMT : 0;
}

/* no modem control lines */
--
2.43.0