mtd: rawnand: sunxi: make the code more self-explanatory

In sunxi_nfc_hw_ecc_{read,write}_chunk(), the ECC step was forced to 0,
the reason is not trivial to get when reading the code.

The explanation is that, from the NAND flash controller perspective, we
are indeed at step 0 for user data length and ECC errors.

Just add a const value with an explanation to clarify things.

Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Richard Genoud <richard.genoud@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Author: richard-bootlin

drivers/mtd/nand/raw/sunxi_nand.c

@@ -963,6 +963,8 @@ static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 	u32 pattern_found;
 	bool erased;
 	int ret;
+	/* From the controller point of view, we are at step 0 */
+	const int nfc_step = 0;
 
 	if (*cur_off != data_off)
 		nand_change_read_column_op(nand, data_off, NULL, 0, false);
@@ -977,7 +979,7 @@ static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 		return ret;
 
 	sunxi_nfc_reset_user_data_len(nfc);
-	sunxi_nfc_set_user_data_len(nfc, USER_DATA_SZ, 0);
+	sunxi_nfc_set_user_data_len(nfc, USER_DATA_SZ, nfc_step);
 	sunxi_nfc_randomizer_config(nand, page, false);
 	sunxi_nfc_randomizer_enable(nand);
 	writel(NFC_DATA_TRANS | NFC_DATA_SWAP_METHOD | NFC_ECC_OP,
@@ -993,10 +995,9 @@ static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 	pattern_found = readl(nfc->regs + nfc->caps->reg_pat_found);
 	pattern_found = field_get(NFC_ECC_PAT_FOUND_MSK(nfc), pattern_found);
 
-	ret = sunxi_nfc_hw_ecc_correct(nand, data, oob_required ? oob : NULL, 0,
-				       readl(nfc->regs + NFC_REG_ECC_ST),
-				       pattern_found,
-				       &erased);
+	ret = sunxi_nfc_hw_ecc_correct(nand, data, oob_required ? oob : NULL,
+				       nfc_step, readl(nfc->regs + NFC_REG_ECC_ST),
+				       pattern_found, &erased);
 	if (erased)
 		return 1;
 
@@ -1029,7 +1030,7 @@ static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 			sunxi_nfc_randomizer_read_buf(nand, oob, ecc->bytes + USER_DATA_SZ,
 						      true, page);
 
-			sunxi_nfc_hw_ecc_get_prot_oob_bytes(nand, oob, 0,
+			sunxi_nfc_hw_ecc_get_prot_oob_bytes(nand, oob, nfc_step,
 							    bbm, page);
 		}
 	}
@@ -1207,6 +1208,8 @@ static int sunxi_nfc_hw_ecc_write_chunk(struct nand_chip *nand,
 	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
 	int ret;
+	/* From the controller point of view, we are at step 0 */
+	const int nfc_step = 0;
 
 	if (data_off != *cur_off)
 		nand_change_write_column_op(nand, data_off, NULL, 0, false);
@@ -1223,8 +1226,8 @@ static int sunxi_nfc_hw_ecc_write_chunk(struct nand_chip *nand,
 	sunxi_nfc_randomizer_config(nand, page, false);
 	sunxi_nfc_randomizer_enable(nand);
 	sunxi_nfc_reset_user_data_len(nfc);
-	sunxi_nfc_set_user_data_len(nfc, USER_DATA_SZ, 0);
-	sunxi_nfc_hw_ecc_set_prot_oob_bytes(nand, oob, 0, bbm, page);
+	sunxi_nfc_set_user_data_len(nfc, USER_DATA_SZ, nfc_step);
+	sunxi_nfc_hw_ecc_set_prot_oob_bytes(nand, oob, nfc_step, bbm, page);
 
 	writel(NFC_DATA_TRANS | NFC_DATA_SWAP_METHOD |
 	       NFC_ACCESS_DIR | NFC_ECC_OP,