sky2: prevent dual port receiver problems
When both ports are receiving simultaneously, the receive logic gets confused
and may pass up a packet before it is full. This causes hangs, and IP will see
lots of garbage packets. There is even the potential for data corruption if
a later arriving packet DMA's into freed memory.
It looks like a hardware bug because status arrives for a packet but no
data is there. Until this bug is worked out, block the user from bringing
up both ports at once.
Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
diff --git a/drivers/net/sky2.c b/drivers/net/sky2.c
index ffd267f..62be6d9 100644
--- a/drivers/net/sky2.c
+++ b/drivers/net/sky2.c
@@ -1020,8 +1020,19 @@
struct sky2_hw *hw = sky2->hw;
unsigned port = sky2->port;
u32 ramsize, rxspace, imask;
- int err = -ENOMEM;
+ int err;
+ struct net_device *otherdev = hw->dev[sky2->port^1];
+ /* Block bringing up both ports at the same time on a dual port card.
+ * There is an unfixed bug where receiver gets confused and picks up
+ * packets out of order. Until this is fixed, prevent data corruption.
+ */
+ if (otherdev && netif_running(otherdev)) {
+ printk(KERN_INFO PFX "dual port support is disabled.\n");
+ return -EBUSY;
+ }
+
+ err = -ENOMEM;
if (netif_msg_ifup(sky2))
printk(KERN_INFO PFX "%s: enabling interface\n", dev->name);