netdev - [net-next-2.6 PATCH 15/15] igb: add flushes between RAR writes when setting mac address

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Date:	Mon, 05 Oct 2009 09:36:01 -0700
From:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:	davem@...emloft.net
Cc:	netdev@...r.kernel.org, gospo@...hat.com,
	Alexander Duyck <alexander.h.duyck@...el.com>,
	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Subject: [net-next-2.6 PATCH 15/15] igb: add flushes between RAR writes when
	setting mac address

From: Alexander Duyck <alexander.h.duyck@...el.com>

There are some switches that will do write combining when they see two
sequential regions written. In order to avoid any possible write combining
issues it is necessary to add a flush after writing each piece of a rar
register.

Signed-off-by: Alexander Duyck <alexander.h.duyck@...el.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
---

 drivers/net/igb/e1000_mac.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/drivers/net/igb/e1000_mac.c b/drivers/net/igb/e1000_mac.c
index 4969a5b..2ad358a 100644
--- a/drivers/net/igb/e1000_mac.c
+++ b/drivers/net/igb/e1000_mac.c
@@ -247,8 +247,15 @@ void igb_rar_set(struct e1000_hw *hw, u8 *addr, u32 index)
 	if (rar_low || rar_high)
 		rar_high |= E1000_RAH_AV;
 
+	/*
+	 * Some bridges will combine consecutive 32-bit writes into
+	 * a single burst write, which will malfunction on some parts.
+	 * The flushes avoid this.
+	 */
 	wr32(E1000_RAL(index), rar_low);
+	wrfl();
 	wr32(E1000_RAH(index), rar_high);
+	wrfl();
 }
 
 /**

--
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