[PATCH 4.19 056/131] cdc-acm: Add DISABLE_ECHO quirk for Microchip/SMSC chip

Sasha Levin
2020-06-29T20:12:56Z

From: Joakim Tjernlund <joakim.tjernlund@infinera.com>

commit 03894573f2913181ee5aae0089f333b2131f2d4b upstream.

USB_DEVICE(0x0424, 0x274e) can send data before cdc_acm is ready,
causing garbage chars on the TTY causing stray input to the shell
and/or login prompt.

Signed-off-by: Joakim Tjernlund <joakim.tjernlund@infinera.com>
Cc: stable@vger.kernel.org
Acked-by: Oliver Neukum <oneukum@suse.com>
Link: https://lore.kernel.org/r/20200605105418.22263-1-joakim.tjernlund@infinera.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/class/cdc-acm.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index e8b9b27937ed6..ea7883e1fbe28 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1721,6 +1721,8 @@ static int acm_pre_reset(struct usb_interface *intf)

static const struct usb_device_id acm_ids[] = {
/* quirky and broken devices */
+ { USB_DEVICE(0x0424, 0x274e), /* Microchip Technology, Inc. (formerly SMSC) */
+ .driver_info = DISABLE_ECHO, }, /* DISABLE ECHO in termios flag */
{ USB_DEVICE(0x076d, 0x0006), /* Denso Cradle CU-321 */
.driver_info = NO_UNION_NORMAL, },/* has no union descriptor */
{ USB_DEVICE(0x17ef, 0x7000), /* Lenovo USB modem */
--
2.25.1