[PATCH v1 29/42] net/e1000/base: improve NVM checksum handling

[Anatoly Burakov]

From: Sasha Neftin <sasha.neftin at intel.com>

When reading NVM checksum, we may encounter the following scenarios:

- Checksum may be invalid, and can be updated
- Checksum may be invalid but cannot be updated because NVM is read-only

For the latter case, we should just ignore invalid checksum and not attempt
to update it.

Signed-off-by: Sasha Neftin <sasha.neftin at intel.com>
Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>
---
 drivers/net/intel/e1000/base/e1000_ich8lan.c | 24 ++++++++++++++------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/net/intel/e1000/base/e1000_ich8lan.c b/drivers/net/intel/e1000/base/e1000_ich8lan.c
index da36d4c098..77c403fa80 100644
--- a/drivers/net/intel/e1000/base/e1000_ich8lan.c
+++ b/drivers/net/intel/e1000/base/e1000_ich8lan.c
@@ -4364,13 +4364,23 @@ STATIC s32 e1000_validate_nvm_checksum_ich8lan(struct e1000_hw *hw)
 		return ret_val;
 
 	if (!(data & valid_csum_mask)) {
-		data |= valid_csum_mask;
-		ret_val = hw->nvm.ops.write(hw, word, 1, &data);
-		if (ret_val)
-			return ret_val;
-		ret_val = hw->nvm.ops.update(hw);
-		if (ret_val)
-			return ret_val;
+		DEBUGOUT("NVM checksum valid bit not set");
+
+		if (hw->mac.type < e1000_pch_tgp) {
+			data |= valid_csum_mask;
+			ret_val = hw->nvm.ops.write(hw, word, 1, &data);
+			if (ret_val)
+				return ret_val;
+			ret_val = hw->nvm.ops.update(hw);
+			if (ret_val)
+				return ret_val;
+		} else if (hw->mac.type == e1000_pch_tgp) {
+			/* Tiger Lake systems may have uninitialized NVM
+			 * checksum. Since the NVM cannot be updated by
+			 * software, do not validate the checksum.
+			 */
+			return E1000_SUCCESS;
+		}
 	}
 
 	return e1000_validate_nvm_checksum_generic(hw);
-- 
2.43.5