I made a patch to make ugen use updated frlengths.
is this ok to commit?

---
YAMAMOTO Takashi<yamt@netbsd.org>

Index: ugen.c
===================================================================
RCS file: /cvs/cvsroot/syssrc/sys/dev/usb/ugen.c,v
retrieving revision 1.45
diff -u -r1.45 ugen.c
--- ugen.c	2000/12/13 04:05:14	1.45
+++ ugen.c	2001/09/16 13:55:16
@@ -822,6 +822,7 @@
 	struct isoreq *req = addr;
 	struct ugen_endpoint *sce = req->sce;
 	u_int32_t count, n;
+	int i, isize;
 
 	/* Return if we are aborting. */
 	if (status == USBD_CANCELLED)
@@ -840,15 +841,25 @@
 			     count));
 	}
 
-	/* copy data to buffer */
-	while (count > 0) {
-		n = min(count, sce->limit - sce->fill);
-		memcpy(sce->fill, req->dmabuf, n);
-
-		count -= n;
-		sce->fill += n;
-		if(sce->fill == sce->limit)
-			sce->fill = sce->ibuf;
+	isize = UGETW(sce->edesc->wMaxPacketSize);
+	for (i = 0; i < UGEN_NISORFRMS; i++) {
+		u_int32_t actlen = req->sizes[i];
+		char const *buf = (char const *)req->dmabuf + isize * i;
+
+		/* copy data to buffer */
+		while (actlen > 0) {
+			n = min(actlen, sce->limit - sce->fill);
+			memcpy(sce->fill, buf, n);
+
+			buf += n;
+			actlen -= n;
+			sce->fill += n;
+			if(sce->fill == sce->limit)
+				sce->fill = sce->ibuf;
+		}
+
+		/* setup size for next transfer */
+		req->sizes[i] = isize;
 	}
 
 	usbd_setup_isoc_xfer(xfer, sce->pipeh, req, req->sizes, UGEN_NISORFRMS,