From bf16cc8f97ff57db191eec73346ba0333ade342b Mon Sep 17 00:00:00 2001
From: aliguori <aliguori@c046a42c-6fe2-441c-8c8c-71466251a162>
Date: Fri, 20 Mar 2009 16:13:47 +0000
Subject: [PATCH] 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 | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/hw/e1000.c b/hw/e1000.c
index e6155d6a69..1644201d6e 100644
--- a/hw/e1000.c
+++ b/hw/e1000.c
@@ -666,8 +666,8 @@ e1000_receive(void *opaque, const uint8_t *buf, int size)
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);
--
2.30.2