commit bf16cc8f97ff57db191eec73346ba0333ade342b
author aliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162> Fri Mar 20 16:13:47 2009 +0000
committer aliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162> Fri Mar 20 16:13:47 2009 +0000
tree 081ee60c6c9b9b801de4b1bebcfdfdb43821bc8b
parent dc1ded53b8cd9198da193e44b25815cdd2ddb6f5

e1000: Fix RX descriptor low threshold interrupt logic (Alex Williamson)

The RXDMT0 interrupt is supposed to fire when the number of free
RX descriptors drops to some fraction of the total descriptors.
However in practice, it seems like we're adding this interrupt
cause on every RX.  Fix the logic to treat (tail - head) as the
number of free entries rather than the number of used entries.

Signed-off-by: Alex Williamson <alex.williamson@hp.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6864 c046a42c-6fe2-441c-8c8c-71466251a162

hw/e1000.c

diff --git a/hw/e1000.c b/hw/e1000.c
index e6155d6..1644201 100644
--- a/hw/e1000.c
+++ b/hw/e1000.c
@@ -666,8 +666,8 @@
     n = E1000_ICS_RXT0;
     if ((rdt = s->mac_reg[RDT]) < s->mac_reg[RDH])
         rdt += s->mac_reg[RDLEN] / sizeof(desc);
-    if (((rdt - s->mac_reg[RDH]) * sizeof(desc)) << s->rxbuf_min_shift >=
-        s->mac_reg[RDLEN])
+    if (((rdt - s->mac_reg[RDH]) * sizeof(desc)) <= s->mac_reg[RDLEN] >>
+        s->rxbuf_min_shift)
         n |= E1000_ICS_RXDMT0;
 
     set_ics(s, 0, n);