ixgbe: check Core Clock Disable bit

This patch corrects the stop_mac_link_on_d3 function in ixgbe_82599 by
checking the Core Clock Disable bit before stopping link.

CC: Arun Sharma <asharma@fb.com>
Reported-by: NChris Pavlas <chris.pavlas@intel.com>
Signed-off-by: NJacob Keller <jacob.e.keller@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_82599.c

@@ -518,8 +518,12 @@ static enum ixgbe_media_type ixgbe_get_media_type_82599(struct ixgbe_hw *hw)
 static void ixgbe_stop_mac_link_on_d3_82599(struct ixgbe_hw *hw)
 {
 	u32 autoc2_reg;
+	u16 ee_ctrl_2 = 0;
 
-	if (!hw->mng_fw_enabled && !hw->wol_enabled) {
+	hw->eeprom.ops.read(hw, IXGBE_EEPROM_CTRL_2, &ee_ctrl_2);
+
+	if (!hw->mng_fw_enabled && !hw->wol_enabled &&
+	    ee_ctrl_2 & IXGBE_EEPROM_CCD_BIT) {
 		autoc2_reg = IXGBE_READ_REG(hw, IXGBE_AUTOC2);
 		autoc2_reg |= IXGBE_AUTOC2_LINK_DISABLE_ON_D3_MASK;
 		IXGBE_WRITE_REG(hw, IXGBE_AUTOC2, autoc2_reg);

drivers/net/ethernet/intel/ixgbe/ixgbe_type.h

@@ -1793,6 +1793,9 @@ enum {
 #define IXGBE_EEPROM_RD_BUFFER_MAX_COUNT 512 /* EEPROM words # read in burst */
 #define IXGBE_EEPROM_WR_BUFFER_MAX_COUNT 256 /* EEPROM words # wr in burst */
 
+#define IXGBE_EEPROM_CTRL_2	1 /* EEPROM CTRL word 2 */
+#define IXGBE_EEPROM_CCD_BIT	2 /* EEPROM Core Clock Disable bit */
+
 #ifndef IXGBE_EEPROM_GRANT_ATTEMPTS
 #define IXGBE_EEPROM_GRANT_ATTEMPTS 1000 /* EEPROM # attempts to gain grant */
 #endif