i = gspca_dev->alt;                     /* previous alt setting */
 
        /* try isoc */
-       while (--i > 0) {                       /* alt 0 is unusable */
+       while (--i >= 0) {
                ep = alt_xfer(&intf->altsetting[i],
                                USB_ENDPOINT_XFER_ISOC);
                if (ep)
                        break;
        }
 
-       /* if no isoc, try bulk */
+       /* if no isoc, try bulk (alt 0 only) */
        if (ep == NULL) {
                ep = alt_xfer(&intf->altsetting[0],
                                USB_ENDPOINT_XFER_BULK);
                        err("no transfer endpoint found");
                        return NULL;
                }
+               i = 0;
+               gspca_dev->bulk = 1;
        }
        PDEBUG(D_STREAM, "use alt %d ep 0x%02x",
                        i, ep->desc.bEndpointAddress);
        /* calculate the packet size and the number of packets */
        psize = le16_to_cpu(ep->desc.wMaxPacketSize);
 
-       if (gspca_dev->alt != 0) {              /* isoc */
+       if (!gspca_dev->bulk) {                 /* isoc */
 
                /* See paragraph 5.9 / table 5-11 of the usb 2.0 spec. */
                psize = (psize & 0x07ff) * (1 + ((psize >> 11) & 3));
                        goto out;
 
                /* clear the bulk endpoint */
-               if (gspca_dev->alt == 0)        /* if bulk transfer */
+               if (gspca_dev->bulk)
                        usb_clear_halt(gspca_dev->dev,
                                        gspca_dev->urb[0]->pipe);
 
                gspca_dev->streaming = 1;
 
                /* some bulk transfers are started by the subdriver */
-               if (gspca_dev->alt == 0 && gspca_dev->cam.bulk_nurbs == 0)
+               if (gspca_dev->bulk && gspca_dev->cam.bulk_nurbs == 0)
                        break;
 
                /* submit the URBs */
 
        __u8 iface;                     /* USB interface number */
        __u8 alt;                       /* USB alternate setting */
        __u8 nbalt;                     /* number of USB alternate settings */
+       u8 bulk;                        /* image transfer by 0:isoc / 1:bulk */
 };
 
 int gspca_dev_probe(struct usb_interface *intf,