Comment 9 for bug 38865

I found this reading netdev mailing list...i think it's closely related to this bug...

[PATCH] sky2: ifdown kills irq mask
Stephen Hemminger
Tue, 09 May 2006 14:47:11 -0700

Bringing down a port also masks off the status and other IRQ's
needed for device to function due to missing paren's.

http://mail-archive.com/netdev%40vger.kernel.org/msg12133.html