memcpy(&endpoint->desc, d, n);
INIT_LIST_HEAD(&endpoint->urb_list);
- /* If the bInterval value is outside the legal range,
- * set it to a default value: 32 ms */
+ /* Fix up bInterval values outside the legal range. Use 32 ms if no
+ * proper value can be guessed. */
i = 0; /* i = min, j = max, n = default */
j = 255;
if (usb_endpoint_xfer_int(d)) {
i = 1;
switch (to_usb_device(ddev)->speed) {
case USB_SPEED_HIGH:
- n = 9; /* 32 ms = 2^(9-1) uframes */
+ /* Many device manufacturers are using full-speed
+ * bInterval values in high-speed interrupt endpoint
+ * descriptors. Try to fix those and fall back to a
+ * 32 ms default value otherwise. */
+ n = fls(d->bInterval*8);
+ if (n == 0)
+ n = 9; /* 32 ms = 2^(9-1) uframes */
j = 16;
break;
default: /* USB_SPEED_FULL or _LOW */
endpoint->desc.bInterval = n;
}
+ /* Some buggy low-speed devices have Bulk endpoints, which is
+ * explicitly forbidden by the USB spec. In an attempt to make
+ * them usable, we will try treating them as Interrupt endpoints.
+ */
+ if (to_usb_device(ddev)->speed == USB_SPEED_LOW &&
+ usb_endpoint_xfer_bulk(d)) {
+ dev_warn(ddev, "config %d interface %d altsetting %d "
+ "endpoint 0x%X is Bulk; changing to Interrupt\n",
+ cfgno, inum, asnum, d->bEndpointAddress);
+ endpoint->desc.bmAttributes = USB_ENDPOINT_XFER_INT;
+ endpoint->desc.bInterval = 1;
+ if (le16_to_cpu(endpoint->desc.wMaxPacketSize) > 8)
+ endpoint->desc.wMaxPacketSize = cpu_to_le16(8);
+ }
+
/* Skip over any Class Specific or Vendor Specific descriptors;
* find the next endpoint or interface descriptor */
endpoint->extra = buffer;