cdc-acm: Add DISABLE_ECHO quirk for Microchip/SMSC chip

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>

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index f67088bb8218b82f9089be2e3d6a3228e77886ca..d5187b50fc82889d771473c1b7e354cea06ce00f 100644 (file)
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1689,6 +1689,8 @@ 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 */