commit 945a51517cc0bd9e461f2018624dfc1faef9ddee
author Jesse Brandeburg <jesse.brandeburg@intel.com> Wed Jul 20 00:56:21 2011 +0000
committer Jeff Kirsher <jeffrey.t.kirsher@intel.com> Thu Aug 04 04:59:07 2011 -0700
tree 5782ffe27f3fb8f5b4cbc19ffe7b74bff36c6a05
parent d3e614577198757d5854caa912e88f2d4296479b

intel drivers: repair missing flush operations

after review of all intel drivers, found several instances where
drivers had the incorrect pattern of:
memory mapped write();
delay();

which should always be:
memory mapped write();
write flush(); /* aka memory mapped read */
delay();

explanation:
The reason for including the flush is that writes can be held
(posted) in PCI/PCIe bridges, but the read always has to complete
synchronously and therefore has to flush all pending writes to a
device.  If a write is held and followed by a delay, the delay
means nothing because the write may not have reached hardware
(maybe even not until the next read)

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by:  Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ixgb/ixgb_ee.c

diff --git a/drivers/net/ixgb/ixgb_ee.c b/drivers/net/ixgb/ixgb_ee.c
index c982ab9..38b362b 100644
--- a/drivers/net/ixgb/ixgb_ee.c
+++ b/drivers/net/ixgb/ixgb_ee.c
@@ -57,6 +57,7 @@
 	 */
 	*eecd_reg = *eecd_reg | IXGB_EECD_SK;
 	IXGB_WRITE_REG(hw, EECD, *eecd_reg);
+	IXGB_WRITE_FLUSH(hw);
 	udelay(50);
 }
 
@@ -75,6 +76,7 @@
 	 */
 	*eecd_reg = *eecd_reg & ~IXGB_EECD_SK;
 	IXGB_WRITE_REG(hw, EECD, *eecd_reg);
+	IXGB_WRITE_FLUSH(hw);
 	udelay(50);
 }
 
@@ -112,6 +114,7 @@
 			eecd_reg |= IXGB_EECD_DI;
 
 		IXGB_WRITE_REG(hw, EECD, eecd_reg);
+		IXGB_WRITE_FLUSH(hw);
 
 		udelay(50);
 
@@ -206,21 +209,25 @@
 	/*  Deselect EEPROM  */
 	eecd_reg &= ~(IXGB_EECD_CS | IXGB_EECD_SK);
 	IXGB_WRITE_REG(hw, EECD, eecd_reg);
+	IXGB_WRITE_FLUSH(hw);
 	udelay(50);
 
 	/*  Clock high  */
 	eecd_reg |= IXGB_EECD_SK;
 	IXGB_WRITE_REG(hw, EECD, eecd_reg);
+	IXGB_WRITE_FLUSH(hw);
 	udelay(50);
 
 	/*  Select EEPROM  */
 	eecd_reg |= IXGB_EECD_CS;
 	IXGB_WRITE_REG(hw, EECD, eecd_reg);
+	IXGB_WRITE_FLUSH(hw);
 	udelay(50);
 
 	/*  Clock low  */
 	eecd_reg &= ~IXGB_EECD_SK;
 	IXGB_WRITE_REG(hw, EECD, eecd_reg);
+	IXGB_WRITE_FLUSH(hw);
 	udelay(50);
 }
 
@@ -239,11 +246,13 @@
 	/*  Rising edge of clock  */
 	eecd_reg |= IXGB_EECD_SK;
 	IXGB_WRITE_REG(hw, EECD, eecd_reg);
+	IXGB_WRITE_FLUSH(hw);
 	udelay(50);
 
 	/*  Falling edge of clock  */
 	eecd_reg &= ~IXGB_EECD_SK;
 	IXGB_WRITE_REG(hw, EECD, eecd_reg);
+	IXGB_WRITE_FLUSH(hw);
 	udelay(50);
 }