1 files changed, 59 insertions, 45 deletions

diff --git a/drivers/usb/serial/cypress_m8.c b/drivers/usb/serial/cypress_m8.c
index bdeda0936951..4bf45c711b9d 100644
--- a/drivers/usb/serial/cypress_m8.c
+++ b/drivers/usb/serial/cypress_m8.c
@@ -291,6 +291,59 @@ static struct usb_serial_driver cypress_ca42v2_device = {
  *****************************************************************************/
 
 
+static int analyze_baud_rate(struct usb_serial_port *port, unsigned baud_mask)
+{
+        int new_rate;
+        struct cypress_private *priv;
+        priv = usb_get_serial_port_data(port);
+
+        /*
+         * The general purpose firmware for the Cypress M8 allows for
+         * a maximum speed of 57600bps (I have no idea whether DeLorme
+         * chose to use the general purpose firmware or not), if you
+         * need to modify this speed setting for your own project
+         * please add your own chiptype and modify the code likewise.
+         * The Cypress HID->COM device will work successfully up to
+         * 115200bps (but the actual throughput is around 3kBps).
+         */
+        new_rate = mask_to_rate(baud_mask);
+        if (new_rate < 0) {
+                dbg("%s - failed setting baud rate, untranslatable speed",
+                    __func__);
+                return -1;
+        }
+        if (port->serial->dev->speed == USB_SPEED_LOW) {
+                /*
+                 * Mike Isely <isely@pobox.com> 2-Feb-2008: The
+                 * Cypress app note that describes this mechanism
+                 * states the the low-speed part can't handle more
+                 * than 800 bytes/sec, in which case 4800 baud is the
+                 * safest speed for a part like that.
+                 */
+                if (new_rate > 4800) {
+                        dbg("%s - failed setting baud rate, device incapable "
+                            "speed %d", __func__, new_rate);
+                        return -1;
+                }
+        }
+        switch (priv->chiptype) {
+        case CT_EARTHMATE:
+                if (new_rate <= 600) {
+                        /* 300 and 600 baud rates are supported under
+                         * the generic firmware, but are not used with
+                         * NMEA and SiRF protocols */
+                        dbg("%s - failed setting baud rate, unsupported speed "
+                            "of %d on Earthmate GPS", __func__, new_rate);
+                        return -1;
+                }
+                break;
+        default:
+                break;
+        }
+        return new_rate;
+}
+
+
 /* This function can either set or retrieve the current serial line settings */
 static int cypress_serial_control (struct usb_serial_port *port, unsigned baud_mask, int data_bits, int stop_bits,
                                    int parity_enable, int parity_type, int reset, int cypress_request_type)
@@ -309,54 +362,15 @@ static int cypress_serial_control (struct usb_serial_port *port, unsigned baud_m
 
         switch(cypress_request_type) {
                 case CYPRESS_SET_CONFIG:
-
-                        /*
-                         * The general purpose firmware for the Cypress M8 allows for a maximum speed
-                         * of 57600bps (I have no idea whether DeLorme chose to use the general purpose
-                         * firmware or not), if you need to modify this speed setting for your own
-                         * project please add your own chiptype and modify the code likewise.  The
-                         * Cypress HID->COM device will work successfully up to 115200bps (but the
-                         * actual throughput is around 3kBps).
-                         */
+                        new_baudrate = priv->baud_rate;
                         if (baud_mask != priv->cbr_mask) {
                                 dbg("%s - baud rate is changing", __FUNCTION__);
-                                if ( priv->chiptype == CT_EARTHMATE ) {
-                                        /* 300 and 600 baud rates are supported under the generic firmware,
-                                         * but are not used with NMEA and SiRF protocols */
-                                        
-                                        if ( (baud_mask == B300) || (baud_mask == B600) ) {
-                                                err("%s - failed setting baud rate, unsupported speed",
-                                                    __FUNCTION__);
-                                                new_baudrate = priv->baud_rate;
-                                        } else if ( (new_baudrate = mask_to_rate(baud_mask)) == -1) {
-                                                err("%s - failed setting baud rate, unsupported speed",
-                                                    __FUNCTION__);
-                                                new_baudrate = priv->baud_rate;
-                                        }
-                                } else if (priv->chiptype == CT_CYPHIDCOM) {
-                                        if ( (new_baudrate = mask_to_rate(baud_mask)) == -1) {
-                                                err("%s - failed setting baud rate, unsupported speed",
-                                                    __FUNCTION__);
-                                                new_baudrate = priv->baud_rate;
-                                        }
-                                } else if (priv->chiptype == CT_CA42V2) {
-                                        if ( (new_baudrate = mask_to_rate(baud_mask)) == -1) {
-                                                err("%s - failed setting baud rate, unsupported speed",
-                                                    __FUNCTION__);
-                                                new_baudrate = priv->baud_rate;
-                                        }
-                                } else if (priv->chiptype == CT_GENERIC) {
-                                        if ( (new_baudrate = mask_to_rate(baud_mask)) == -1) {
-                                                err("%s - failed setting baud rate, unsupported speed",
-                                                    __FUNCTION__);
-                                                new_baudrate = priv->baud_rate;
-                                        }
-                                } else {
-                                        info("%s - please define your chiptype", __FUNCTION__);
-                                        new_baudrate = priv->baud_rate;
+                                retval = analyze_baud_rate(port, baud_mask);
+                                if (retval >=  0) {
+                                        new_baudrate = retval;
+                                        dbg("%s - New baud rate set to %d",
+                                            __func__, new_baudrate);
                                 }
-                        } else {  /* baud rate not changing, keep the old */
-                                new_baudrate = priv->baud_rate;
                         }
                         dbg("%s - baud rate is being sent as %d", __FUNCTION__, new_baudrate);