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>
diff --git a/drivers/net/e1000/e1000_hw.c b/drivers/net/e1000/e1000_hw.c
index 1698622..8545c7a 100644
--- a/drivers/net/e1000/e1000_hw.c
+++ b/drivers/net/e1000/e1000_hw.c
@@ -446,6 +446,7 @@
/* Must reset the PHY before resetting the MAC */
if ((hw->mac_type == e1000_82541) || (hw->mac_type == e1000_82547)) {
ew32(CTRL, (ctrl | E1000_CTRL_PHY_RST));
+ E1000_WRITE_FLUSH();
msleep(5);
}
@@ -3752,6 +3753,7 @@
/* Clear SK and CS */
eecd &= ~(E1000_EECD_CS | E1000_EECD_SK);
ew32(EECD, eecd);
+ E1000_WRITE_FLUSH();
udelay(1);
}
@@ -3824,6 +3826,7 @@
eecd &= ~E1000_EECD_SK; /* Lower SCK */
ew32(EECD, eecd);
+ E1000_WRITE_FLUSH();
udelay(hw->eeprom.delay_usec);
} else if (hw->eeprom.type == e1000_eeprom_microwire) {