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, 4 insertions, 0 deletions

diff --git a/drivers/net/e1000e/ich8lan.c b/drivers/net/e1000e/ich8lan.c
index c1752124f3cd..f7a75c1531ad 100644
--- a/drivers/net/e1000e/ich8lan.c
+++ b/drivers/net/e1000e/ich8lan.c
@@ -283,6 +283,7 @@ static void e1000_toggle_lanphypc_value_ich8lan(struct e1000_hw *hw)
         ctrl |= E1000_CTRL_LANPHYPC_OVERRIDE;
         ctrl &= ~E1000_CTRL_LANPHYPC_VALUE;
         ew32(CTRL, ctrl);
+        e1e_flush();
         udelay(10);
         ctrl &= ~E1000_CTRL_LANPHYPC_OVERRIDE;
         ew32(CTRL, ctrl);
@@ -1230,9 +1231,11 @@ s32 e1000_configure_k1_ich8lan(struct e1000_hw *hw, bool k1_enable)
         ew32(CTRL, reg);
 
         ew32(CTRL_EXT, ctrl_ext | E1000_CTRL_EXT_SPD_BYPS);
+        e1e_flush();
         udelay(20);
         ew32(CTRL, ctrl_reg);
         ew32(CTRL_EXT, ctrl_ext);
+        e1e_flush();
         udelay(20);
 
 out:
@@ -3090,6 +3093,7 @@ static s32 e1000_reset_hw_ich8lan(struct e1000_hw *hw)
         ret_val = e1000_acquire_swflag_ich8lan(hw);
         e_dbg("Issuing a global reset to ich8lan\n");
         ew32(CTRL, (ctrl | E1000_CTRL_RST));
+        /* cannot issue a flush here because it hangs the hardware */
         msleep(20);
 
         if (!ret_val)