diff --git a/drivers/mtd/nand/raw/sunxi_nand.c b/drivers/mtd/nand/raw/sunxi_nand.c
index 9dc742ee4344..1c1fcea69108 100644
--- a/drivers/mtd/nand/raw/sunxi_nand.c
+++ b/drivers/mtd/nand/raw/sunxi_nand.c
@@ -996,35 +996,59 @@ static void sunxi_nfc_reset_user_data_len(struct sunxi_nfc *nfc)
 		writel(0, nfc->regs + NFC_REG_USER_DATA_LEN(nfc, i));
 }
 
-static void sunxi_nfc_set_user_data_len(struct sunxi_nfc *nfc,
-					int len, int hw_step)
+static int sunxi_nfc_user_data_len_code(struct sunxi_nfc *nfc, int len)
 {
-	bool found = false;
-	u32 val;
 	int i;
 
+	for (i = 0; i < nfc->caps->nuser_data_tab; i++) {
+		if (len == nfc->caps->user_data_len_tab[i])
+			return i;
+	}
+
+	dev_warn(nfc->dev, "Unsupported length for user data reg: %d\n", len);
+	return -EINVAL;
+}
+
+static void sunxi_nfc_set_user_data_len_pio(struct sunxi_nfc *nfc, int len)
+{
+	int code;
+
 	/* not all SoCs have this register */
 	if (!nfc->caps->reg_user_data_len)
 		return;
 
-	for (i = 0; i < nfc->caps->nuser_data_tab; i++) {
-		if (len == nfc->caps->user_data_len_tab[i]) {
-			found = true;
-			break;
-		}
-	}
-
-	if (!found) {
-		dev_warn(nfc->dev,
-			 "Unsupported length for user data reg: %d\n", len);
+	code = sunxi_nfc_user_data_len_code(nfc, len);
+	if (code < 0)
 		return;
-	}
 
-	val = readl(nfc->regs + NFC_REG_USER_DATA_LEN(nfc, hw_step));
+	/* PIO uses slot zero; the page callback clears all other slots. */
+	writel(FIELD_PREP(NFC_USER_DATA_LEN_MSK(0), code),
+	       nfc->regs + NFC_REG_USER_DATA_LEN(nfc, 0));
+}
+
+static void sunxi_nfc_set_user_data_len_dma(struct nand_chip *nand, int nchunks)
+{
+	struct sunxi_nand_chip *sunxi_nand = to_sunxi_nand(nand);
+	struct sunxi_nfc *nfc = to_sunxi_nfc(nand->controller);
+	int first, step, len, code;
+	u32 val;
+
+	if (!nfc->caps->reg_user_data_len)
+		return;
 
-	val &= ~NFC_USER_DATA_LEN_MSK(hw_step);
-	val |= field_prep(NFC_USER_DATA_LEN_MSK(hw_step), i);
-	writel(val, nfc->regs + NFC_REG_USER_DATA_LEN(nfc, hw_step));
+	/* Write each packed register once, including zeroes for unused slots. */
+	for (first = 0; first < nfc->caps->max_ecc_steps;
+	     first += NFC_REG_USER_DATA_LEN_CAPACITY) {
+		val = 0;
+		for (step = first; step < nchunks &&
+		     step < first + NFC_REG_USER_DATA_LEN_CAPACITY; step++) {
+			len = sunxi_nfc_user_data_sz(sunxi_nand, step);
+			code = sunxi_nfc_user_data_len_code(nfc, len);
+			if (code >= 0)
+				val |= field_prep(NFC_USER_DATA_LEN_MSK(step), code);
+		}
+		writel(val, nfc->regs + NFC_REG_USER_DATA_LEN(nfc, first));
+	}
 }
 
 static void sunxi_nfc_hw_ecc_set_prot_oob_bytes(struct nand_chip *nand,
@@ -1213,7 +1237,7 @@ static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 	if (ret)
 		return ret;
 
-	sunxi_nfc_set_user_data_len(nfc, user_data_sz, hw_step);
+	sunxi_nfc_set_user_data_len_pio(nfc, user_data_sz);
 	sunxi_nfc_randomizer_config(nand, page, false);
 	sunxi_nfc_randomizer_enable(nand);
 	writel(NFC_DATA_TRANS | NFC_DATA_SWAP_METHOD | NFC_ECC_OP,
@@ -1524,9 +1548,7 @@ static int sunxi_nfc_hw_ecc_read_chunks_dma(struct nand_chip *nand, uint8_t *buf
 		return ret;
 
 	sunxi_nfc_hw_ecc_enable(nand);
-	sunxi_nfc_reset_user_data_len(nfc);
-	for (i = 0; i < nchunks; i++)
-		sunxi_nfc_set_user_data_len(nfc, sunxi_nfc_user_data_sz(sunxi_nand, i), i);
+	sunxi_nfc_set_user_data_len_dma(nand, nchunks);
 	sunxi_nfc_randomizer_config(nand, page, false);
 	sunxi_nfc_randomizer_enable(nand);
 
@@ -1682,7 +1704,7 @@ 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_set_user_data_len(nfc, user_data_sz, hw_step);
+	sunxi_nfc_set_user_data_len_pio(nfc, user_data_sz);
 	sunxi_nfc_hw_ecc_set_prot_oob_bytes(nand, oob, hw_step, bbm, page,
 					    user_data_sz);
 
@@ -1977,7 +1999,7 @@ static int sunxi_nfc_hw_ecc_write_page_dma(struct nand_chip *nand,
 	if (ret)
 		goto pio_fallback;
 
-	sunxi_nfc_reset_user_data_len(nfc);
+	sunxi_nfc_set_user_data_len_dma(nand, ecc->steps);
 	for (i = 0; i < ecc->steps; i++) {
 		unsigned int user_data_sz = sunxi_nfc_user_data_sz(sunxi_nand, i);
 		int oob_off = sunxi_get_oob_offset(sunxi_nand, ecc, i);
@@ -1985,7 +2007,6 @@ static int sunxi_nfc_hw_ecc_write_page_dma(struct nand_chip *nand,
 
 		sunxi_nfc_hw_ecc_set_prot_oob_bytes(nand, oob, i, !i, page,
 						    user_data_sz);
-		sunxi_nfc_set_user_data_len(nfc, user_data_sz, i);
 	}
 
 	ret = nand_prog_page_begin_op(nand, page, 0, NULL, 0);