e1000e: clear REQ and GNT in EECD (82571 && 82572)

Clear the REQ and GNT bit in the eeprom control register (EECD).
This is required if the eeprom is to be accessed with auto read
EERD register.

After a cold reset this doesn't matter but if PBIST MAC test was
executed before booting, the register was left in a dirty state
(the 2 bits where set), which caused the read operation to time out
and returning 0.

Reference (page 312):
http://download.intel.com/design/network/manuals/316080.pdf

Reported-by: Aleksandar Igic <aleksandar.igic@dektech.com.au>
Signed-off-by: Richard Alpe <richard.alpe@ericsson.com>
Tested-by: Jeff Pieper <jeffrey.e.pieper@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/e1000e/82571.c b/drivers/net/ethernet/intel/e1000e/82571.c
index 6a8a908f92b813fbe6838f5222161691bcd381c6..36db4df09aed6531cf66d893b40449a1b0cceb2c 100644 (file)
--- a/drivers/net/ethernet/intel/e1000e/82571.c
+++ b/drivers/net/ethernet/intel/e1000e/82571.c
@@ -999,7 +999,7 @@ static s32 e1000_set_d0_lplu_state_82571(struct e1000_hw *hw, bool active)
  **/
 static s32 e1000_reset_hw_82571(struct e1000_hw *hw)
 {
-       u32 ctrl, ctrl_ext;
+       u32 ctrl, ctrl_ext, eecd;
        s32 ret_val;
 
        /*
@@ -1072,6 +1072,16 @@ static s32 e1000_reset_hw_82571(struct e1000_hw *hw)
         */
 
        switch (hw->mac.type) {
+       case e1000_82571:
+       case e1000_82572:
+               /*
+                * REQ and GNT bits need to be cleared when using AUTO_RD
+                * to access the EEPROM.
+                */
+               eecd = er32(EECD);
+               eecd &= ~(E1000_EECD_REQ | E1000_EECD_GNT);
+               ew32(EECD, eecd);
+               break;
        case e1000_82573:
        case e1000_82574:
        case e1000_82583: