i40e: Fix for NUP NVM image downgrade failure

Since commit 96a39ae ("i40e: Acquire NVM lock before
reads on all devices") we've used the NVM lock
to synchronize NVM reads even on devices which don't strictly
need the lock.

Doing so can cause a regression on older firmware prior to 1.5,
especially when downgrading the firmware.

Fix this by only grabbing the lock if we're running on an X722
device (which requires the lock as it uses the AdminQ to read
the NVM), or if we're currently running 1.5 or newer firmware.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e_adminq.c

@@ -613,6 +613,12 @@ i40e_status i40e_init_adminq(struct i40e_hw *hw)
 		hw->flags |= I40E_HW_FLAG_AQ_PHY_ACCESS_CAPABLE;
 	}
 
+	/* Newer versions of firmware require lock when reading the NVM */
+	if (hw->aq.api_maj_ver > 1 ||
+	    (hw->aq.api_maj_ver == 1 &&
+	     hw->aq.api_min_ver >= 5))
+		hw->flags |= I40E_HW_FLAG_NVM_READ_REQUIRES_LOCK;
+
 	/* The ability to RX (not drop) 802.1ad frames was added in API 1.7 */
 	if (hw->aq.api_maj_ver > 1 ||
 	    (hw->aq.api_maj_ver == 1 &&

drivers/net/ethernet/intel/i40e/i40e_common.c

@@ -948,7 +948,8 @@ i40e_status i40e_init_shared_code(struct i40e_hw *hw)
 		hw->pf_id = (u8)(func_rid & 0x7);
 
 	if (hw->mac.type == I40E_MAC_X722)
-		hw->flags |= I40E_HW_FLAG_AQ_SRCTL_ACCESS_ENABLE;
+		hw->flags |= I40E_HW_FLAG_AQ_SRCTL_ACCESS_ENABLE |
+			     I40E_HW_FLAG_NVM_READ_REQUIRES_LOCK;
 
 	status = i40e_init_nvm(hw);
 	return status;

drivers/net/ethernet/intel/i40e/i40e_nvm.c

@@ -328,15 +328,17 @@ static i40e_status __i40e_read_nvm_word(struct i40e_hw *hw,
 i40e_status i40e_read_nvm_word(struct i40e_hw *hw, u16 offset,
 			       u16 *data)
 {
-	i40e_status ret_code;
+	i40e_status ret_code = 0;
 
-	ret_code = i40e_acquire_nvm(hw, I40E_RESOURCE_READ);
+	if (hw->flags & I40E_HW_FLAG_NVM_READ_REQUIRES_LOCK)
+		ret_code = i40e_acquire_nvm(hw, I40E_RESOURCE_READ);
 	if (ret_code)
 		return ret_code;
 
 	ret_code = __i40e_read_nvm_word(hw, offset, data);
 
-	i40e_release_nvm(hw);
+	if (hw->flags & I40E_HW_FLAG_NVM_READ_REQUIRES_LOCK)
+		i40e_release_nvm(hw);
 
 	return ret_code;
 }

drivers/net/ethernet/intel/i40e/i40e_type.h

@@ -629,6 +629,7 @@ struct i40e_hw {
 #define I40E_HW_FLAG_AQ_SRCTL_ACCESS_ENABLE BIT_ULL(0)
 #define I40E_HW_FLAG_802_1AD_CAPABLE        BIT_ULL(1)
 #define I40E_HW_FLAG_AQ_PHY_ACCESS_CAPABLE  BIT_ULL(2)
+#define I40E_HW_FLAG_NVM_READ_REQUIRES_LOCK BIT_ULL(3)
 	u64 flags;
 
 	/* Used in set switch config AQ command */