linux-kernel - [PATCH 7/9] serial: st-asc: Sanitize CSIZE and correct PARENB for CS7

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Message-Id: <20220517110737.37148-8-ilpo.jarvinen@linux.intel.com>
Date:   Tue, 17 May 2022 14:07:35 +0300
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     linux-serial@...r.kernel.org, Greg KH <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Patrice Chotard <patrice.chotard@...s.st.com>,
        Srinivas Kandagatla <srinivas.kandagatla@...com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Subject: [PATCH 7/9] serial: st-asc: Sanitize CSIZE and correct PARENB for CS7

Only CS7 and CS8 seem supported but CSIZE is not sanitized from CS5 or
CS6 to CS8. In addition, ASC_CTL_MODE_7BIT_PAR suggests that CS7 has
to have parity, thus add PARENB.

Incorrect CSIZE results in miscalculation of the frame bits in
tty_get_char_size() or in its predecessor where the roughly the same
code is directly within uart_update_timeout().

Cc: Srinivas Kandagatla <srinivas.kandagatla@...com>
Fixes: c4b058560762 (serial:st-asc: Add ST ASC driver.)
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---
 drivers/tty/serial/st-asc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/tty/serial/st-asc.c b/drivers/tty/serial/st-asc.c
index d7fd692286cf..1b0da603ab54 100644
--- a/drivers/tty/serial/st-asc.c
+++ b/drivers/tty/serial/st-asc.c
@@ -535,10 +535,14 @@ static void asc_set_termios(struct uart_port *port, struct ktermios *termios,
 	/* set character length */
 	if ((cflag & CSIZE) == CS7) {
 		ctrl_val |= ASC_CTL_MODE_7BIT_PAR;
+		cflag |= PARENB;
 	} else {
 		ctrl_val |= (cflag & PARENB) ?  ASC_CTL_MODE_8BIT_PAR :
 						ASC_CTL_MODE_8BIT;
+		cflag &= ~CSIZE;
+		cflag |= CS8;
 	}
+	termios->c_cflag = cflag;
 
 	/* set stop bit */
 	ctrl_val |= (cflag & CSTOPB) ? ASC_CTL_STOP_2BIT : ASC_CTL_STOP_1BIT;
-- 
2.30.2