netdev - [net-2.6 PATCH 5/6] e1000e: delay second read of PHY_STATUS register on failure of first read

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Message-ID: <20090701232850.20555.69711.stgit@localhost.localdomain>
Date:	Wed, 01 Jul 2009 16:28:50 -0700
From:	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
To:	davem@...emloft.net
Cc:	netdev@...r.kernel.org, gospo@...hat.com,
	Bruce Allan <bruce.w.allan@...el.com>,
	Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Subject: [net-2.6 PATCH 5/6] e1000e: delay second read of PHY_STATUS register
	on failure of first read

From: Bruce Allan <bruce.w.allan@...el.com>

Some PHYs may require two reads of the PHY_STATUS register to determine the
link status.  If the PHY is being accessed by another thread it is possible
the first read could timeout and fail.  In this case, put a delay in so
the second read will pick up the correct link status.

Signed-off-by: Bruce Allan <bruce.w.allan@...el.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
---

 drivers/net/e1000e/phy.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/drivers/net/e1000e/phy.c b/drivers/net/e1000e/phy.c
index d845394..994401f 100644
--- a/drivers/net/e1000e/phy.c
+++ b/drivers/net/e1000e/phy.c
@@ -1531,7 +1531,12 @@ s32 e1000e_phy_has_link_generic(struct e1000_hw *hw, u32 iterations,
 		 */
 		ret_val = e1e_rphy(hw, PHY_STATUS, &phy_status);
 		if (ret_val)
-			break;
+			/*
+			 * If the first read fails, another entity may have
+			 * ownership of the resources, wait and try again to
+			 * see if they have relinquished the resources yet.
+			 */
+			udelay(usec_interval);
 		ret_val = e1e_rphy(hw, PHY_STATUS, &phy_status);
 		if (ret_val)
 			break;

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