USB: serial: cp210x: fix partnum regression

When adding GPIO support for the cp2105, the mentioned commit by Martyn
Welch introduced a query for the part number of the chip. Unfortunately
the driver aborts probing when this query fails, so currently the driver
can not be used with chips not supporting this query.
I have a data cable for Siemens mobile phones (ID 10ab:10c5) where this
is the case.
With this patch the driver can be bound even if the part number can not
be queried.

Fixes: cf5276ce7867 ("USB: serial: cp210x: Adding GPIO support for CP2105")
Signed-off-by: Sebastian Frei <dr.nop@gmx.net>
[ johan: amend commit message; shorten error message and demote to
         warning; drop unnecessary move of usb_set_serial_data() ]
Cc: stable <stable@vger.kernel.org>	# 4.9
Signed-off-by: Johan Hovold <johan@kernel.org>

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index 2d945c9f975c04d5cd7909e00a37017a97e8062e..8364b44f4c45fb0972296d3ab3d034c05f99cc4a 100644 (file)
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -352,6 +352,7 @@ static struct usb_serial_driver * const serial_drivers[] = {
 #define CP210X_PARTNUM_CP2104  0x04
 #define CP210X_PARTNUM_CP2105  0x05
 #define CP210X_PARTNUM_CP2108  0x08
+#define CP210X_PARTNUM_UNKNOWN 0xFF
 
 /* CP210X_GET_COMM_STATUS returns these 0x13 bytes */
 struct cp210x_comm_status {
@@ -1491,8 +1492,11 @@ static int cp210x_attach(struct usb_serial *serial)
        result = cp210x_read_vendor_block(serial, REQTYPE_DEVICE_TO_HOST,
                                          CP210X_GET_PARTNUM, &priv->partnum,
                                          sizeof(priv->partnum));
-       if (result < 0)
-               goto err_free_priv;
+       if (result < 0) {
+               dev_warn(&serial->interface->dev,
+                        "querying part number failed\n");
+               priv->partnum = CP210X_PARTNUM_UNKNOWN;
+       }
 
        usb_set_serial_data(serial, priv);
 
@@ -1505,10 +1509,6 @@ static int cp210x_attach(struct usb_serial *serial)
        }
 
        return 0;
-err_free_priv:
-       kfree(priv);
-
-       return result;
 }
 
 static void cp210x_disconnect(struct usb_serial *serial)