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>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/net/ixgbe/ixgbe_x540.c b/drivers/net/ixgbe/ixgbe_x540.c
index bec30ed91adc..2696c78e9f46 100644
--- a/drivers/net/ixgbe/ixgbe_x540.c
+++ b/drivers/net/ixgbe/ixgbe_x540.c
@@ -162,6 +162,7 @@ mac_reset_top:
 	ctrl_ext = IXGBE_READ_REG(hw, IXGBE_CTRL_EXT);
 	ctrl_ext |= IXGBE_CTRL_EXT_PFRSTD;
 	IXGBE_WRITE_REG(hw, IXGBE_CTRL_EXT, ctrl_ext);
+	IXGBE_WRITE_FLUSH(hw);
 
 	msleep(50);