ixgbe: force unlock on timeout

The semaphore can be in locked state upon driver load, particularly
on 82598 if a machine is rebooted due to panic and the semaphore was
acquired just prior to the panic.

This patch unlocks the semaphore if it times out.

Signed-off-by: Emil Tantilov <[e-mail]>
Signed-off-by: Jeff Kirsher <[e-mail]>

drivers/net/ixgbe/ixgbe_common.c

···
 		udelay(50);
 	}
 
+	if (i == timeout) {
+		hw_dbg(hw, "Driver can't access the Eeprom - SMBI Semaphore "
+		       "not granted.\n");
+		/*
+		 * this release is particularly important because our attempts
+		 * above to get the semaphore may have succeeded, and if there
+		 * was a timeout, we should unconditionally clear the semaphore
+		 * bits to free the driver to make progress
+		 */
+		ixgbe_release_eeprom_semaphore(hw);
+
+		udelay(50);
+		/*
+		 * one last try
+		 * If the SMBI bit is 0 when we read it, then the bit will be
+		 * set and we have the semaphore
+		 */
+		swsm = IXGBE_READ_REG(hw, IXGBE_SWSM);
+		if (!(swsm & IXGBE_SWSM_SMBI))
+			status = 0;
+	}
+
 	/* Now get the semaphore between SW/FW through the SWESMBI bit */
 	if (status == 0) {
 		for (i = 0; i < timeout; i++) {