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, 2 insertions, 0 deletions

diff --git a/drivers/net/ixgb/ixgb_hw.c b/drivers/net/ixgb/ixgb_hw.c
index 6cb2e42ff4c1..3d61a9e4faf7 100644
--- a/drivers/net/ixgb/ixgb_hw.c
+++ b/drivers/net/ixgb/ixgb_hw.c
@@ -149,6 +149,7 @@ ixgb_adapter_stop(struct ixgb_hw *hw)
 	 */
 	IXGB_WRITE_REG(hw, RCTL, IXGB_READ_REG(hw, RCTL) & ~IXGB_RCTL_RXEN);
 	IXGB_WRITE_REG(hw, TCTL, IXGB_READ_REG(hw, TCTL) & ~IXGB_TCTL_TXEN);
+	IXGB_WRITE_FLUSH(hw);
 	msleep(IXGB_DELAY_BEFORE_RESET);
 
 	/* Issue a global reset to the MAC.  This will reset the chip's
@@ -1220,6 +1221,7 @@ ixgb_optics_reset_bcm(struct ixgb_hw *hw)
 	ctrl &= ~IXGB_CTRL0_SDP2;
 	ctrl |= IXGB_CTRL0_SDP3;
 	IXGB_WRITE_REG(hw, CTRL0, ctrl);
+	IXGB_WRITE_FLUSH(hw);
 
 	/* SerDes needs extra delay */
 	msleep(IXGB_SUN_PHY_RESET_DELAY);