USB: Fix up full-speed bInterval values in high-speed interrupt descriptor

Many device manufacturers are using full-speed bInterval values in high-speed
interrupt endpoint descriptors. If the bInterval value is greater than 16,
assume the device uses full-speed descriptors and fix the value accordingly.

Signed-off-by: Laurent Pinchart <laurent.pinchart@skynet.be>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 9 insertions, 3 deletions

diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
index 9152e12dcf71..5e113db41b59 100644
--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -85,15 +85,21 @@ static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum,
         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 */