patch "USB: ftdi_sio: fixed handling of unsupported CSIZE setting" added to usb tree

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This is a note to let you know that I've just added the patch titled

    USB: ftdi_sio: fixed handling of unsupported CSIZE setting

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 8704211f65a2106ba01b6ac9727cdaf9ca11594c Mon Sep 17 00:00:00 2001
From: Colin Leitner <colin.leitner@xxxxxxxxxxxxxx>
Date: Tue, 5 Nov 2013 18:02:34 +0100
Subject: USB: ftdi_sio: fixed handling of unsupported CSIZE setting

FTDI UARTs support only 7 or 8 data bits. Until now the ftdi_sio driver would
only report this limitation for CS6 to dmesg and fail to reflect this fact to
tcgetattr.

This patch reverts the unsupported CSIZE setting and reports the fact with less
severance to dmesg for both CS5 and CS6.

To test the patch it's sufficient to call

    stty -F /dev/ttyUSB0 cs5

which will succeed without the patch and report an error with the patch
applied.

As an additional fix this patch ensures that the control request will always
include a data bit size.

Signed-off-by: Colin Leitner <colin.leitner@xxxxxxxxx>
Signed-off-by: Johan Hovold <jhovold@xxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/usb/serial/ftdi_sio.c | 37 ++++++++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 9ced8937a8f3..fb0d537435eb 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -2123,6 +2123,20 @@ static void ftdi_set_termios(struct tty_struct *tty,
 		termios->c_cflag |= CRTSCTS;
 	}
 
+	/*
+	 * All FTDI UART chips are limited to CS7/8. We won't pretend to
+	 * support CS5/6 and revert the CSIZE setting instead.
+	 */
+	if ((C_CSIZE(tty) != CS8) && (C_CSIZE(tty) != CS7)) {
+		dev_warn(ddev, "requested CSIZE setting not supported\n");
+
+		termios->c_cflag &= ~CSIZE;
+		if (old_termios)
+			termios->c_cflag |= old_termios->c_cflag & CSIZE;
+		else
+			termios->c_cflag |= CS8;
+	}
+
 	cflag = termios->c_cflag;
 
 	if (!old_termios)
@@ -2159,19 +2173,16 @@ no_skip:
 	} else {
 		urb_value |= FTDI_SIO_SET_DATA_PARITY_NONE;
 	}
-	if (cflag & CSIZE) {
-		switch (cflag & CSIZE) {
-		case CS7:
-			urb_value |= 7;
-			dev_dbg(ddev, "Setting CS7\n");
-			break;
-		case CS8:
-			urb_value |= 8;
-			dev_dbg(ddev, "Setting CS8\n");
-			break;
-		default:
-			dev_err(ddev, "CSIZE was set but not CS7-CS8\n");
-		}
+	switch (cflag & CSIZE) {
+	case CS7:
+		urb_value |= 7;
+		dev_dbg(ddev, "Setting CS7\n");
+		break;
+	default:
+	case CS8:
+		urb_value |= 8;
+		dev_dbg(ddev, "Setting CS8\n");
+		break;
 	}
 
 	/* This is needed by the break command since it uses the same command
-- 
1.8.5.rc3


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