1 files changed, 38 insertions, 0 deletions

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index 66a6ac50a4cd..189279869a8b 100644
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -233,6 +233,7 @@ static const struct usb_device_id id_table[] = {
 	{ USB_DEVICE(0x1FB9, 0x0602) }, /* Lake Shore Model 648 Magnet Power Supply */
 	{ USB_DEVICE(0x1FB9, 0x0700) }, /* Lake Shore Model 737 VSM Controller */
 	{ USB_DEVICE(0x1FB9, 0x0701) }, /* Lake Shore Model 776 Hall Matrix */
+	{ USB_DEVICE(0x2184, 0x0030) }, /* GW Instek GDM-834x Digital Multimeter */
 	{ USB_DEVICE(0x2626, 0xEA60) }, /* Aruba Networks 7xxx USB Serial Console */
 	{ USB_DEVICE(0x3195, 0xF190) }, /* Link Instruments MSO-19 */
 	{ USB_DEVICE(0x3195, 0xF280) }, /* Link Instruments MSO-28 */
@@ -258,6 +259,7 @@ struct cp210x_serial_private {
 	speed_t			max_speed;
 	bool			use_actual_rate;
 	bool			no_flow_control;
+	bool			no_event_mode;
 };
 
 enum cp210x_event_state {
@@ -1113,12 +1115,16 @@ static void cp210x_change_speed(struct tty_struct *tty,
 
 static void cp210x_enable_event_mode(struct usb_serial_port *port)
 {
+	struct cp210x_serial_private *priv = usb_get_serial_data(port->serial);
 	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
 	int ret;
 
 	if (port_priv->event_mode)
 		return;
 
+	if (priv->no_event_mode)
+		return;
+
 	port_priv->event_state = ES_DATA;
 	port_priv->event_mode = true;
 
@@ -2074,6 +2080,33 @@ static void cp210x_init_max_speed(struct usb_serial *serial)
 	priv->use_actual_rate = use_actual_rate;
 }
 
+static void cp2102_determine_quirks(struct usb_serial *serial)
+{
+	struct cp210x_serial_private *priv = usb_get_serial_data(serial);
+	u8 *buf;
+	int ret;
+
+	buf = kmalloc(2, GFP_KERNEL);
+	if (!buf)
+		return;
+	/*
+	 * Some (possibly counterfeit) CP2102 do not support event-insertion
+	 * mode and respond differently to malformed vendor requests.
+	 * Specifically, they return one instead of two bytes when sent a
+	 * two-byte part-number request.
+	 */
+	ret = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
+			CP210X_VENDOR_SPECIFIC, REQTYPE_DEVICE_TO_HOST,
+			CP210X_GET_PARTNUM, 0, buf, 2, USB_CTRL_GET_TIMEOUT);
+	if (ret == 1) {
+		dev_dbg(&serial->interface->dev,
+				"device does not support event-insertion mode\n");
+		priv->no_event_mode = true;
+	}
+
+	kfree(buf);
+}
+
 static int cp210x_get_fw_version(struct usb_serial *serial, u16 value)
 {
 	struct cp210x_serial_private *priv = usb_get_serial_data(serial);
@@ -2108,7 +2141,12 @@ static void cp210x_determine_type(struct usb_serial *serial)
 		return;
 	}
 
+	dev_dbg(&serial->interface->dev, "partnum = 0x%02x\n", priv->partnum);
+
 	switch (priv->partnum) {
+	case CP210X_PARTNUM_CP2102:
+		cp2102_determine_quirks(serial);
+		break;
 	case CP210X_PARTNUM_CP2105:
 	case CP210X_PARTNUM_CP2108:
 		cp210x_get_fw_version(serial, CP210X_GET_FW_VER);