apply a fix by Steven Chamberlain <steven@pyro.eu.org>, via freebsd:

Fix an issue with 11g beacon frames which looks to be a limitation
on the largest multi-write size:

==
I looked further into the magic 88-byte threshold after which the bug
occurs.  It turns out that figure included the 24-byte tx_desc, and up
to 64 bytes of beacon frame (header+data).

rum_write_multi doesn't seem happy with writing >64 bytes at a time to
the MAC register.  If I break it up into separate calls (e.g. bytes
0-63, then bytes 64-65, written at the appropriate offset) I see the
proper beacon frames being transmitted now.
==

tweak by miod@
ok deraadt@

1 files changed, 12 insertions, 7 deletions

diff --git a/sys/dev/usb/if_rum.c b/sys/dev/usb/if_rum.c
index c561600d584..6d5b495dde4 100644
--- a/sys/dev/usb/if_rum.c
+++ b/sys/dev/usb/if_rum.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_rum.c,v 1.98 2011/07/03 15:47:17 matthew Exp $	*/
+/*	$OpenBSD: if_rum.c,v 1.99 2011/10/26 17:31:54 jasper Exp $	*/
 
 /*-
  * Copyright (c) 2005-2007 Damien Bergamini <damien.bergamini@free.fr>
@@ -1486,17 +1486,22 @@ rum_write_multi(struct rum_softc *sc, uint16_t reg, void *buf, size_t len)
 {
 	usb_device_request_t req;
 	usbd_status error;
+	int offset;
 
 	req.bmRequestType = UT_WRITE_VENDOR_DEVICE;
 	req.bRequest = RT2573_WRITE_MULTI_MAC;
 	USETW(req.wValue, 0);
-	USETW(req.wIndex, reg);
-	USETW(req.wLength, len);
 
-	error = usbd_do_request(sc->sc_udev, &req, buf);
-	if (error != 0) {
-		printf("%s: could not multi write MAC register: %s\n",
-		    sc->sc_dev.dv_xname, usbd_errstr(error));
+	/* write at most 64 bytes at a time */
+	for (offset = 0; offset < len; offset += 64) {
+		USETW(req.wIndex, reg + offset);
+		USETW(req.wLength, MIN(len - offset, 64));
+
+		error = usbd_do_request(sc->sc_udev, &req, buf + offset);
+		if (error != 0) {
+			printf("%s: could not multi write MAC register: %s\n",
+			    sc->sc_dev.dv_xname, usbd_errstr(error));
+		}
 	}
 }