diff mbox series

[v6,09/18] mtd: rawnand: sunxi: use page reads to reposition small-page NAND

Message ID 20260914-submit-sunxi-nand-vendor-oob-layout-v1-v6-9-2fb084fe0751@gmail.com (mailing list archive)
State New
Headers
Series mtd: rawnand: sunxi: support the Allwinner randomized OOB format |

Commit Message

James Hilliard Sept. 14, 2026, 9:09 p.m. UTC 
The hardware-ECC read paths use random-column commands to revisit main
data and OOB. Small-page NAND does not support these commands, and
nand_change_read_column_op() rejects pages of 512 bytes or less. Ignoring
that error does not provide a physical reread: the erased-chunk check can
instead inspect stale buffer contents.

Introduce a read-column helper which starts a new page read for small-page
NAND. Let the NAND core select READ0, READ1 or READOOB and send the row
address. Keep random-column commands for large pages. Pass the page number
through the erased-chunk fallback and use the helper for normal OOB reads
as well.

Retain transport errors and only classify a physical chunk after all its
rereads succeed. Read exactly the requested region so the tracked column
still matches the start of any trailing OOB.

Also select PIO callbacks for small-page hardware ECC even when DMA is
available. The DMA page sequencer uses large-page random-column commands;
PIO can stream the single 512-byte ECC step and its OOB without them.

Keep the ECC geometry checks unchanged. In particular, the usual 512+16
geometry still cannot fit the controller's minimum 28 parity bytes and
four user-data bytes. This fixes the command handling for small-page
geometries that pass those checks, not a demonstrated regression on a
previously working 512+16 device. Software-ECC and raw callbacks,
large-page DMA eligibility and the on-flash layout are unchanged.

Fixes: 1fef62c1423b ("mtd: nand: add sunxi NAND flash controller support")
Fixes: 614049a8d904 ("mtd: nand: sunxi: add support for DMA assisted operations")
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
 drivers/mtd/nand/raw/sunxi_nand.c | 40 +++++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 16 deletions(-)
diff mbox series

Patch

diff --git a/drivers/mtd/nand/raw/sunxi_nand.c b/drivers/mtd/nand/raw/sunxi_nand.c
index 13dc0af56eb3..e29638c828ca 100644
--- a/drivers/mtd/nand/raw/sunxi_nand.c
+++ b/drivers/mtd/nand/raw/sunxi_nand.c
@@ -1079,6 +1079,16 @@  static void sunxi_nfc_hw_ecc_update_stats(struct nand_chip *nand,
 	}
 }
 
+static int sunxi_nfc_read_column(struct nand_chip *nand, int page,
+				 unsigned int column, void *buf, unsigned int len)
+{
+	/* Small-page NAND needs a new READ0/READ1/READOOB and the page address. */
+	if (nand_to_mtd(nand)->writesize <= 512)
+		return nand_read_page_op(nand, page, column, buf, len);
+
+	return nand_change_read_column_op(nand, column, buf, len, false);
+}
+
 /*
  * Return 1 for an erased chunk or 0 for an uncorrectable chunk, with ECC
  * statistics updated in either case. Negative values report transport errors.
@@ -1087,7 +1097,7 @@  static int sunxi_nfc_hw_ecc_read_error(struct nand_chip *nand,
 				       u8 *data, int data_off,
 				       u8 *oob, int oob_off,
 				       unsigned int user_data_sz,
-				       unsigned int *max_bitflips)
+				       unsigned int *max_bitflips, int page)
 {
 	struct nand_ecc_ctrl *ecc = &nand->ecc;
 	unsigned int oob_len = ecc->bytes + user_data_sz;
@@ -1095,13 +1105,12 @@  static int sunxi_nfc_hw_ecc_read_error(struct nand_chip *nand,
 
 	/* Check the physical representation for bitflips in erased pages. */
 	if (nand->options & NAND_NEED_SCRAMBLING) {
-		ret = nand_change_read_column_op(nand, data_off, data,
-						 ecc->size, false);
+		ret = sunxi_nfc_read_column(nand, page, data_off, data, ecc->size);
 		if (ret)
 			return ret;
 	}
 
-	ret = nand_change_read_column_op(nand, oob_off, oob, oob_len, false);
+	ret = sunxi_nfc_read_column(nand, page, oob_off, oob, oob_len);
 	if (ret)
 		return ret;
 
@@ -1169,7 +1178,7 @@  static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 	const int nfc_step = 0;
 
 	if (*cur_off != data_off) {
-		ret = nand_change_read_column_op(nand, data_off, NULL, 0, false);
+		ret = sunxi_nfc_read_column(nand, page, data_off, NULL, 0);
 		if (ret)
 			return ret;
 	}
@@ -1179,7 +1188,7 @@  static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 		return ret;
 
 	if (data_off + ecc->size != oob_off) {
-		ret = nand_change_read_column_op(nand, oob_off, NULL, 0, false);
+		ret = sunxi_nfc_read_column(nand, page, oob_off, NULL, 0);
 		if (ret)
 			return ret;
 	}
@@ -1217,13 +1226,12 @@  static int sunxi_nfc_hw_ecc_read_chunk(struct nand_chip *nand,
 
 		return sunxi_nfc_hw_ecc_read_error(nand, data, data_off,
 						 oob, oob_off, user_data_sz,
-						 max_bitflips);
+						 max_bitflips, page);
 	} else {
 		memcpy_fromio(data, nfc->regs + NFC_RAM0_BASE, ecc->size);
 
 		if (oob_required) {
-			ret = nand_change_read_column_op(nand, oob_off, NULL, 0,
-							 false);
+			ret = sunxi_nfc_read_column(nand, page, oob_off, NULL, 0);
 			if (ret)
 				return ret;
 			ret = sunxi_nfc_randomizer_read_buf(nand, oob,
@@ -1285,8 +1293,8 @@  static int sunxi_nfc_hw_ecc_read_extra_oob(struct nand_chip *nand,
 		return 0;
 
 	if (!cur_off || *cur_off != (offset + mtd->writesize)) {
-		ret = nand_change_read_column_op(nand, mtd->writesize + offset,
-						 NULL, 0, false);
+		ret = sunxi_nfc_read_column(nand, page, mtd->writesize + offset,
+					    NULL, 0);
 		if (ret)
 			return ret;
 	}
@@ -1386,9 +1394,8 @@  static int sunxi_nfc_hw_ecc_read_chunks_dma(struct nand_chip *nand, uint8_t *buf
 
 		if (oob_required && !erased) {
 			/* TODO: use DMA to retrieve OOB */
-			ret = nand_change_read_column_op(nand, mtd->writesize + oob_off,
-							 oob, ecc->bytes + user_data_sz,
-							 false);
+			ret = sunxi_nfc_read_column(nand, page, mtd->writesize + oob_off,
+						    oob, ecc->bytes + user_data_sz);
 			if (ret)
 				goto err_stats;
 
@@ -1416,7 +1423,7 @@  static int sunxi_nfc_hw_ecc_read_chunks_dma(struct nand_chip *nand, uint8_t *buf
 			ret = sunxi_nfc_hw_ecc_read_error(nand, data, data_off, oob,
 							  mtd->writesize + oob_off,
 							  user_data_sz,
-							  &max_bitflips);
+							  &max_bitflips, page);
 			if (ret < 0)
 				goto err_stats;
 			if (ret)
@@ -2305,7 +2312,8 @@  static int sunxi_nand_hw_ecc_ctrl_init(struct nand_chip *nand,
 	ecc->write_oob = sunxi_nfc_hw_ecc_write_oob;
 	mtd_set_ooblayout(mtd, &sunxi_nand_ooblayout_ops);
 
-	if (nfc->dmac || nfc->use_mdma) {
+	/* The DMA page sequencer uses large-page random-column commands. */
+	if (mtd->writesize > 512 && (nfc->dmac || nfc->use_mdma)) {
 		ecc->read_page = sunxi_nfc_hw_ecc_read_page_dma;
 		ecc->read_subpage = sunxi_nfc_hw_ecc_read_subpage_dma;
 		ecc->write_page = sunxi_nfc_hw_ecc_write_page_dma;