Revert "USB: xhci - fix math in xhci_get_endpoint_interval()"

This reverts commit fe3bf5f4be7d3a1a61225c77bd8a9b51baa3ac19.

Due to a reported problem with USB3 after application of three patches
from upstream stable, these patches are being reverted until they can
be tested seperately and a determination made of whether there is a
problem and how bad it is. The reporter has not yet responded to a
request to test kernels with each of the most suspect patches reverted,
so all will be reverted. Testing will proceed using these patches and
hopefully they can be restored soon. The USB3 problem was reported
in LP bug number 769042

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 0de3100..a953439 100644 (file)
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -920,47 +920,6 @@ int xhci_setup_addressable_virt_dev(struct xhci_hcd *xhci, struct usb_device *ud
        return 0;
 }
 
-/*
- * Convert interval expressed as 2^(bInterval - 1) == interval into
- * straight exponent value 2^n == interval.
- *
- */
-static unsigned int xhci_parse_exponent_interval(struct usb_device *udev,
-               struct usb_host_endpoint *ep)
-{
-       unsigned int interval;
-
-       interval = clamp_val(ep->desc.bInterval, 1, 16) - 1;
-       if (interval != ep->desc.bInterval - 1)
-               dev_warn(&udev->dev,
-                        "ep %#x - rounding interval to %d microframes\n",
-                        ep->desc.bEndpointAddress,
-                        1 << interval);
-
-       return interval;
-}
-
-/*
- * Convert bInterval expressed in frames (in 1-255 range) to exponent of
- * microframes, rounded down to nearest power of 2.
- */
-static unsigned int xhci_parse_frame_interval(struct usb_device *udev,
-               struct usb_host_endpoint *ep)
-{
-       unsigned int interval;
-
-       interval = fls(8 * ep->desc.bInterval) - 1;
-       interval = clamp_val(interval, 3, 10);
-       if ((1 << interval) != 8 * ep->desc.bInterval)
-               dev_warn(&udev->dev,
-                        "ep %#x - rounding interval to %d microframes, ep desc says %d microframes\n",
-                        ep->desc.bEndpointAddress,
-                        1 << interval,
-                        8 * ep->desc.bInterval);
-
-       return interval;
-}
-
 /* Return the polling or NAK interval.
  *
  * The polling interval is expressed in "microframes".  If xHCI's Interval field
@@ -978,38 +937,45 @@ static inline unsigned int xhci_get_endpoint_interval(struct usb_device *udev,
        case USB_SPEED_HIGH:
                /* Max NAK rate */
                if (usb_endpoint_xfer_control(&ep->desc) ||
-                   usb_endpoint_xfer_bulk(&ep->desc)) {
+                               usb_endpoint_xfer_bulk(&ep->desc))
                        interval = ep->desc.bInterval;
-                       break;
-               }
                /* Fall through - SS and HS isoc/int have same decoding */
-
        case USB_SPEED_SUPER:
                if (usb_endpoint_xfer_int(&ep->desc) ||
-                   usb_endpoint_xfer_isoc(&ep->desc)) {
-                       interval = xhci_parse_exponent_interval(udev, ep);
+                               usb_endpoint_xfer_isoc(&ep->desc)) {
+                       if (ep->desc.bInterval == 0)
+                               interval = 0;
+                       else
+                               interval = ep->desc.bInterval - 1;
+                       if (interval > 15)
+                               interval = 15;
+                       if (interval != ep->desc.bInterval + 1)
+                               dev_warn(&udev->dev, "ep %#x - rounding interval to %d microframes\n",
+                                               ep->desc.bEndpointAddress, 1 << interval);
                }
                break;
-
+       /* Convert bInterval (in 1-255 frames) to microframes and round down to
+        * nearest power of 2.
+        */
        case USB_SPEED_FULL:
-               if (usb_endpoint_xfer_int(&ep->desc)) {
-                       interval = xhci_parse_exponent_interval(udev, ep);
-                       break;
-               }
-               /*
-                * Fall through for isochronous endpoint interval decoding
-                * since it uses the same rules as low speed interrupt
-                * endpoints.
-                */
-
        case USB_SPEED_LOW:
                if (usb_endpoint_xfer_int(&ep->desc) ||
-                   usb_endpoint_xfer_isoc(&ep->desc)) {
-
-                       interval = xhci_parse_frame_interval(udev, ep);
+                               usb_endpoint_xfer_isoc(&ep->desc)) {
+                       interval = fls(8*ep->desc.bInterval) - 1;
+                       if (interval > 10)
+                               interval = 10;
+                       if (interval < 3)
+                               interval = 3;
+                       if ((1 << interval) != 8*ep->desc.bInterval)
+                               dev_warn(&udev->dev,
+                                               "ep %#x - rounding interval"
+                                               " to %d microframes, "
+                                               "ep desc says %d microframes\n",
+                                               ep->desc.bEndpointAddress,
+                                               1 << interval,
+                                               8*ep->desc.bInterval);
                }
                break;
-
        default:
                BUG();
        }