[net-next v2 04/11] i40e: ShadowRAM checksum calculation change

[Jeff Kirsher <jeffrey.t.kirsher@intel.com>]

From: Maciej Paczkowski <maciej.paczkowski@intel.com>

Due to changes in FW the SW is required to perform double SR dump in
some cases.

Implementation adds two new steps to update nvm checksum function:
* recalculate checksum and check if checksum in NVM is correct
* if checksum in NVM is not correct then update it again

Signed-off-by: Maciej Paczkowski <maciej.paczkowski@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_nvm.c | 29 +++++++++++++++++++---
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_nvm.c b/drivers/net/ethernet/intel/i40e/i40e_nvm.c
index 0299e5bbb902..ee89779a9a6f 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_nvm.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_nvm.c
@@ -574,13 +574,34 @@ static i40e_status i40e_calc_nvm_checksum(struct i40e_hw *hw,
 i40e_status i40e_update_nvm_checksum(struct i40e_hw *hw)
 {
 	i40e_status ret_code;
-	u16 checksum;
+	u16 checksum, checksum_sr;
 	__le16 le_sum;
 
 	ret_code = i40e_calc_nvm_checksum(hw, &checksum);
-	if (!ret_code) {
-		le_sum = cpu_to_le16(checksum);
-		ret_code = i40e_write_nvm_aq(hw, 0x00, I40E_SR_SW_CHECKSUM_WORD,
+	if (ret_code)
+		return ret_code;
+
+	le_sum = cpu_to_le16(checksum);
+	ret_code = i40e_write_nvm_aq(hw, 0x00, I40E_SR_SW_CHECKSUM_WORD,
+				     1, &le_sum, true);
+	if (ret_code)
+		return ret_code;
+
+	/* Due to changes in FW the SW is required to perform double SR-dump
+	 * in some cases. SR-dump is the process when internal shadow RAM is
+	 * dumped into flash bank. It is triggered by setting "last_command"
+	 * argument in i40e_write_nvm_aq function call.
+	 * Since FW 1.8 we need to calculate SR checksum again and update it
+	 * in flash if it is not equal to previously computed checksum.
+	 * This situation would occur only in FW >= 1.8
+	 */
+	ret_code = i40e_calc_nvm_checksum(hw, &checksum_sr);
+	if (ret_code)
+		return ret_code;
+	if (checksum_sr != checksum) {
+		le_sum = cpu_to_le16(checksum_sr);
+		ret_code = i40e_write_nvm_aq(hw, 0x00,
+					     I40E_SR_SW_CHECKSUM_WORD,
 					     1, &le_sum, true);
 	}
 
-- 
2.20.1