[PATCH 4.19 136/148] tty: serial: samsung: fix tx_empty() to return TIOCSER_TEMT

[Sasha Levin]

From: Tudor Ambarus <tudor.ambarus@xxxxxxxxxx>

[ 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@xxxxxxxxxx>
Reviewed-by: Sam Protsenko <semen.protsenko@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240119104526.1221243-2-tudor.ambarus@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/tty/serial/samsung.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index 5f1f52cc63951..c76bf1c11e6fd 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -800,11 +800,10 @@ 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