ixgbe: clear semaphore bits on timeouts

This patch changes the error code path in ixgbe_acquire_swfw_sync() to deal
with cases where acquiring SW semaphore times out.

In cases where the SW/FW semaphore bits were set (i.e. due to a crash) the
driver will hang on load. With this patch the driver will clear
the stuck bits if the semaphore was not acquired in the allotted time.
Signed-off-by: Emil Tantilov <emil.s.tantilov@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

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

@@ -2506,42 +2506,39 @@ static s32 ixgbe_disable_pcie_master(struct ixgbe_hw *hw)
  **/
 s32 ixgbe_acquire_swfw_sync(struct ixgbe_hw *hw, u16 mask)
 {
-	u32 gssr;
+	u32 gssr = 0;
 	u32 swmask = mask;
 	u32 fwmask = mask << 5;
-	s32 timeout = 200;
+	u32 timeout = 200;
+	u32 i;
 
-	while (timeout) {
+	for (i = 0; i < timeout; i++) {
 		/*
-		 * SW EEPROM semaphore bit is used for access to all
-		 * SW_FW_SYNC/GSSR bits (not just EEPROM)
+		 * SW NVM semaphore bit is used for access to all
+		 * SW_FW_SYNC bits (not just NVM)
 		 */
 		if (ixgbe_get_eeprom_semaphore(hw))
 			return IXGBE_ERR_SWFW_SYNC;
 
 		gssr = IXGBE_READ_REG(hw, IXGBE_GSSR);
-		if (!(gssr & (fwmask | swmask)))
-			break;
-
-		/*
-		 * Firmware currently using resource (fwmask) or other software
-		 * thread currently using resource (swmask)
-		 */
+		if (!(gssr & (fwmask | swmask))) {
+			gssr |= swmask;
+			IXGBE_WRITE_REG(hw, IXGBE_GSSR, gssr);
+			ixgbe_release_eeprom_semaphore(hw);
+			return 0;
+		} else {
+			/* Resource is currently in use by FW or SW */
 			ixgbe_release_eeprom_semaphore(hw);
 			usleep_range(5000, 10000);
-		timeout--;
 		}
-
-	if (!timeout) {
-		hw_dbg(hw, "Driver can't access resource, SW_FW_SYNC timeout.\n");
-		return IXGBE_ERR_SWFW_SYNC;
 	}
 
-	gssr |= swmask;
-	IXGBE_WRITE_REG(hw, IXGBE_GSSR, gssr);
+	/* If time expired clear the bits holding the lock and retry */
+	if (gssr & (fwmask | swmask))
+		ixgbe_release_swfw_sync(hw, gssr & (fwmask | swmask));
 
-	ixgbe_release_eeprom_semaphore(hw);
-	return 0;
+	usleep_range(5000, 10000);
+	return IXGBE_ERR_SWFW_SYNC;
 }
 
 /**