USB: musb: use right poll limit for low speed devices
authorSergei Shtylyov <sshtylyov@ru.mvista.com>
Sat, 21 Feb 2009 23:31:35 +0000 (15:31 -0800)
committerGreg Kroah-Hartman <gregkh@suse.de>
Fri, 27 Feb 2009 22:40:51 +0000 (14:40 -0800)
Remove wrongly applied upper limit on the interrupt transfer
interval for low speed devices (not much of an error per se,
according to USB specs).

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
drivers/usb/musb/musb_host.c

index 23d3890fd54de9d5a8a1334d511b129e3f0c6fa2..6dbbd0786a6a0955877dca888f107b641d50eec0 100644 (file)
@@ -1863,19 +1863,21 @@ static int musb_urb_enqueue(
        }
        qh->type_reg = type_reg;
 
-       /* precompute rxinterval/txinterval register */
-       interval = min((u8)16, epd->bInterval); /* log encoding */
+       /* Precompute RXINTERVAL/TXINTERVAL register */
        switch (qh->type) {
        case USB_ENDPOINT_XFER_INT:
-               /* fullspeed uses linear encoding */
-               if (USB_SPEED_FULL == urb->dev->speed) {
-                       interval = epd->bInterval;
-                       if (!interval)
-                               interval = 1;
+               /*
+                * Full/low speeds use the  linear encoding,
+                * high speed uses the logarithmic encoding.
+                */
+               if (urb->dev->speed <= USB_SPEED_FULL) {
+                       interval = max_t(u8, epd->bInterval, 1);
+                       break;
                }
                /* FALLTHROUGH */
        case USB_ENDPOINT_XFER_ISOC:
-               /* iso always uses log encoding */
+               /* ISO always uses logarithmic encoding */
+               interval = min_t(u8, epd->bInterval, 16);
                break;
        default:
                /* REVISIT we actually want to use NAK limits, hinting to the