Date: Wed, 24 Sep 2003 23:48:46 -0400 From: Andrew Atrens <atrens@nortelnetworks.com> To: stable@freebsd.org Subject: fix/workaround for usb probe lockups on nForce2 mbs Message-ID: <3F72659E.8090809@nortelnetworks.com>
next in thread | raw e-mail | index | archive | help
This is a multi-part message in MIME format.
--------------030403060902050201080906
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
All,
The attached patch fixes the boot lockups I've been experiencing on my
nForce2 (A7N8X-Deluxe) motherboards when usb devices are on the bus at
boot time.
Looks like something in usb_explore is (inadvertently?) enabling
interrupts if it detects a device on a port. The fix is, during hub
attach, to not assume that interrupts are off when we access the hub in
'polling' mode.
Not sure if this is a fix or a workaround. I'll leave that to the usb
gods to decide ...
At any rate, I'd appreciate some feedback ... nForce2 users, does this
work for you ?
Cheers,
Andrew.
--------------030403060902050201080906
Content-Type: text/plain;
name="usb.c.patch"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
filename="usb.c.patch"
--- ../usb.good/usb.c Mon Aug 25 21:22:33 2003
+++ usb.c Wed Sep 24 23:22:56 2003
@@ -243,11 +243,24 @@
* Turning this code off will delay attachment of USB devices
* until the USB event thread is running, which means that
* the keyboard will not work until after cold boot.
+ *
+ * On nForce2/ohci interrupts get enabled while use_polling
+ * is set to true. When this happens the cpu spins servicing
+ * the interrupt routine repeatedly and the restart locks
+ * solid. This appears to be a race condition as it only
+ * happens when devices are connected prior to boot - indeed
+ * with no devices attached the lockup doesn't happen.
+ *
+ * Don't take any chances and use splusb() to make sure we
+ * don't start receiving interrupts before we are ready for
+ * them ...
*/
if (cold) {
+ int s = splusb();
sc->sc_bus->use_polling++;
dev->hub->explore(sc->sc_bus->root_hub);
sc->sc_bus->use_polling--;
+ splx( s );
}
#endif
} else {
--------------030403060902050201080906--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3F72659E.8090809>