[PATCH AUTOSEL 4.14 105/170] tty: serial: samsung: Properly set flags in autoCTS mode

Sasha Levin
2019-01-28T16:16:39Z

From: Beomho Seo <beomho.seo@samsung.com>

[ Upstream commit 31e933645742ee6719d37573a27cce0761dcf92b ]

Commit 391f93f2ec9f ("serial: core: Rework hw-assited flow control support")
has changed the way the autoCTS mode is handled.

According to that change, serial drivers which enable H/W autoCTS mode must
set UPSTAT_AUTOCTS to prevent the serial core from inadvertently disabling
TX. This patch adds proper handling of UPSTAT_AUTOCTS flag.

Signed-off-by: Beomho Seo <beomho.seo@samsung.com>
[mszyprow: rephrased commit message]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/tty/serial/samsung.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index 57baa84ccf86..f4b8e4e17a86 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -1343,11 +1343,14 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
wr_regl(port, S3C2410_ULCON, ulcon);
wr_regl(port, S3C2410_UBRDIV, quot);

+ port->status &= ~UPSTAT_AUTOCTS;
+
umcon = rd_regl(port, S3C2410_UMCON);
if (termios->c_cflag & CRTSCTS) {
umcon |= S3C2410_UMCOM_AFC;
/* Disable RTS when RX FIFO contains 63 bytes */
umcon &= ~S3C2412_UMCON_AFC_8;
+ port->status = UPSTAT_AUTOCTS;
} else {
umcon &= ~S3C2410_UMCOM_AFC;
}
--
2.19.1