USB-serial: pl2303: use 1.5 instead of 2 stop bits with 5 data bits

This is how "real" UARTs (e.g. 16550) work and AFAIK what RS232 specifies, too.
Make the driver more compliant.

Signed-off-by: Frank Schaefer <schaefer.frank@gmx.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 10 insertions, 2 deletions

diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 6ed33c7e53e2..1128e01525b1 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -622,8 +622,16 @@ static void pl2303_set_termios(struct tty_struct *tty,
         /* For reference buf[4]=1 is 1.5 stop bits */
         /* For reference buf[4]=2 is 2 stop bits */
         if (cflag & CSTOPB) {
-                buf[4] = 2;
-                dbg("%s - stop bits = 2", __func__);
+                /* NOTE: Comply with "real" UARTs / RS232:
+                 *       use 1.5 instead of 2 stop bits with 5 data bits
+                 */
+                if ((cflag & CSIZE) == CS5) {
+                        buf[4] = 1;
+                        dbg("%s - stop bits = 1.5", __func__);
+                } else {
+                        buf[4] = 2;
+                        dbg("%s - stop bits = 2", __func__);
+                }
         } else {
                 buf[4] = 0;
                 dbg("%s - stop bits = 1", __func__);