[PATCH 05/10] net/e1000/base: clear DPG enable bit post MAC reset

[Ciara Loftus <ciara.loftus@intel.com>]

From: Vitaly Lifshits <vitaly.lifshits@intel.com>

The GbE autonomous power gating feature was added to support G3 to S5
flow. However, this changed the reset value of DPG_EN bit to 1, causing
a possible autonomous transition to power gating state during D0. This
might result in undefined errors such as: packet loss, packet corruption
and Tx/Rx hangs. Therefore, clear DPG_EN bit after hardware reset flow.

Signed-off-by: Vitaly Lifshits <vitaly.lifshits@intel.com>
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>
---
 drivers/net/intel/e1000/base/e1000_defines.h | 1 +
 drivers/net/intel/e1000/base/e1000_ich8lan.c | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/net/intel/e1000/base/e1000_defines.h b/drivers/net/intel/e1000/base/e1000_defines.h
index eb93675823..6c710300a6 100644
--- a/drivers/net/intel/e1000/base/e1000_defines.h
+++ b/drivers/net/intel/e1000/base/e1000_defines.h
@@ -36,6 +36,7 @@
 
 /* Extended Device Control */
 #define E1000_CTRL_EXT_LPCD		0x00000004 /* LCD Power Cycle Done */
+#define E1000_CTRL_EXT_DPG_EN		0x00000008 /* Dynamic Power Gating Enable */
 #define E1000_CTRL_EXT_SDP4_DATA	0x00000010 /* SW Definable Pin 4 data */
 #define E1000_CTRL_EXT_SDP6_DATA	0x00000040 /* SW Definable Pin 6 data */
 #define E1000_CTRL_EXT_SDP3_DATA	0x00000080 /* SW Definable Pin 3 data */
diff --git a/drivers/net/intel/e1000/base/e1000_ich8lan.c b/drivers/net/intel/e1000/base/e1000_ich8lan.c
index 6190052368..96b9ad6a70 100644
--- a/drivers/net/intel/e1000/base/e1000_ich8lan.c
+++ b/drivers/net/intel/e1000/base/e1000_ich8lan.c
@@ -5107,6 +5107,13 @@ STATIC s32 e1000_reset_hw_ich8lan(struct e1000_hw *hw)
 	reg |= E1000_KABGTXD_BGSQLBIAS;
 	E1000_WRITE_REG(hw, E1000_KABGTXD, reg);
 
+	if (hw->mac.type >= e1000_pch_ptp) {
+		DEBUGOUT("Clearing DPG EN bit post reset\n");
+		reg = E1000_READ_REG(hw, E1000_CTRL_EXT);
+		reg &= ~E1000_CTRL_EXT_DPG_EN;
+		E1000_WRITE_REG(hw, E1000_CTRL_EXT, reg);
+	}
+
 	return E1000_SUCCESS;
 }
 
-- 
2.43.0