[PATCH 1/3] mtd: nand: mxc: Fix failed/corrected values

[Sascha Hauer]

Currently nand_read_page_hwecc() from nand_base calls
mxc_nand_correct_data_v2_v3() for each subpage, but in this function we
return the corrected/failed results for the whole page instead
of a single subpage. On a 2k page size Nand this leads to results which
are 4 times too high.
The whole ecc.calculate/ecc.correct mechanism used by
nand_read_page_hwecc() is not suitable for devices which correct the
data in hardware, so fix this by using a driver specific read_page
function which does the right thing.

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 drivers/mtd/nand/mxc_nand.c | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
index f3be0b2a8869..65d5cde4692b 100644
--- a/drivers/mtd/nand/mxc_nand.c
+++ b/drivers/mtd/nand/mxc_nand.c
@@ -140,6 +140,8 @@ struct mxc_nand_host;
 
 struct mxc_nand_devtype_data {
 	void (*preset)(struct mtd_info *);
+	int (*read_page)(struct mtd_info *mtd, struct nand_chip *chip,
+			uint8_t *buf, int oob_required, int page);
 	void (*send_cmd)(struct mxc_nand_host *, uint16_t, int);
 	void (*send_addr)(struct mxc_nand_host *, uint16_t, int);
 	void (*send_page)(struct mtd_info *, unsigned int);
@@ -617,13 +619,23 @@ static int mxc_nand_correct_data_v1(struct mtd_info *mtd, u_char *dat,
 static int mxc_nand_correct_data_v2_v3(struct mtd_info *mtd, u_char *dat,
 				 u_char *read_ecc, u_char *calc_ecc)
 {
-	struct nand_chip *nand_chip = mtd_to_nand(mtd);
-	struct mxc_nand_host *host = nand_get_controller_data(nand_chip);
+	return 0;
+}
+
+static int mxc_nand_read_page_hwecc_v2_v3(struct mtd_info *mtd,
+					  struct nand_chip *chip,
+					  uint8_t *buf, int oob_required,
+					  int page)
+{
+	struct mxc_nand_host *host = nand_get_controller_data(chip);
+	unsigned int max_bitflips = 0;
 	u32 ecc_stat, err;
-	int no_subpages = 1;
-	int ret = 0;
+	int no_subpages;
 	u8 ecc_bit_mask, err_limit;
 
+	chip->read_buf(mtd, buf, mtd->writesize);
+	chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
+
 	ecc_bit_mask = (host->eccsize == 4) ? 0x7 : 0xf;
 	err_limit = (host->eccsize == 4) ? 0x4 : 0x8;
 
@@ -634,17 +646,16 @@ static int mxc_nand_correct_data_v2_v3(struct mtd_info *mtd, u_char *dat,
 	do {
 		err = ecc_stat & ecc_bit_mask;
 		if (err > err_limit) {
-			dev_dbg(host->dev, "UnCorrectable RS-ECC Error\n");
-			return -EBADMSG;
+			mtd->ecc_stats.failed++;
 		} else {
-			ret += err;
+			mtd->ecc_stats.corrected += err;
+			max_bitflips = max_t(unsigned int, max_bitflips, err);
 		}
+
 		ecc_stat >>= 4;
 	} while (--no_subpages);
 
-	dev_dbg(host->dev, "%d Symbol Correctable RS-ECC Error\n", ret);
-
-	return ret;
+	return max_bitflips;
 }
 
 static int mxc_nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat,
@@ -1444,6 +1455,7 @@ static const struct mxc_nand_devtype_data imx27_nand_devtype_data = {
 /* v21: i.MX25, i.MX35 */
 static const struct mxc_nand_devtype_data imx25_nand_devtype_data = {
 	.preset = preset_v2,
+	.read_page = mxc_nand_read_page_hwecc_v2_v3,
 	.send_cmd = send_cmd_v1_v2,
 	.send_addr = send_addr_v1_v2,
 	.send_page = send_page_v2,
@@ -1469,6 +1481,7 @@ static const struct mxc_nand_devtype_data imx25_nand_devtype_data = {
 /* v3.2a: i.MX51 */
 static const struct mxc_nand_devtype_data imx51_nand_devtype_data = {
 	.preset = preset_v3,
+	.read_page = mxc_nand_read_page_hwecc_v2_v3,
 	.send_cmd = send_cmd_v3,
 	.send_addr = send_addr_v3,
 	.send_page = send_page_v3,
@@ -1494,6 +1507,7 @@ static const struct mxc_nand_devtype_data imx51_nand_devtype_data = {
 /* v3.2b: i.MX53 */
 static const struct mxc_nand_devtype_data imx53_nand_devtype_data = {
 	.preset = preset_v3,
+	.read_page = mxc_nand_read_page_hwecc_v2_v3,
 	.send_cmd = send_cmd_v3,
 	.send_addr = send_addr_v3,
 	.send_page = send_page_v3,
@@ -1751,6 +1765,7 @@ static int mxcnd_probe(struct platform_device *pdev)
 
 	switch (this->ecc.mode) {
 	case NAND_ECC_HW:
+		this->ecc.read_page = host->devtype_data->read_page;
 		this->ecc.calculate = mxc_nand_calculate_ecc;
 		this->ecc.hwctl = mxc_nand_enable_hwecc;
 		this->ecc.correct = host->devtype_data->correct_data;
-- 
2.11.0