mtd/spinand: sync core spinand code with linux-5.10.118

This brings us closer to the current Linux kernel implementation of
the spinand core and makes backporting features and fixes easier.

This does not include the latest kernel implementation as this would
require a substantial amount of extra work due to the missing
ECC engine abstraction layer in U-Boot.

Signed-off-by: Mikhail Kshevetskiy <[email protected]>
Signed-off-by: Frieder Schrempf <[email protected]> (add commit message)
Link: https://lore.kernel.org/all/[email protected]
Signed-off-by: Dario Binacchi <[email protected]>

drivers/mtd/nand/spi/core.c

@@ -327,6 +327,13 @@ static int spinand_write_to_cache_op(struct spinand_device *spinand,
 	u16 column = 0;
 	int ret;
 
+	/*
+	 * Looks like PROGRAM LOAD (AKA write cache) does not necessarily reset
+	 * the cache content to 0xFF (depends on vendor implementation), so we
+	 * must fill the page cache entirely even if we only want to program
+	 * the data portion of the page, otherwise we might corrupt the BBM or
+	 * user data previously programmed in OOB area.
+	 */
 	memset(spinand->databuf, 0xff,
 	       nanddev_page_size(nand) +
 	       nanddev_per_page_oobsize(nand));
@@ -599,12 +606,12 @@ static int spinand_mtd_read(struct mtd_info *mtd, loff_t from,
 		if (ret == -EBADMSG) {
 			ecc_failed = true;
 			mtd->ecc_stats.failed++;
-			ret = 0;
 		} else {
 			mtd->ecc_stats.corrected += ret;
 			max_bitflips = max_t(unsigned int, max_bitflips, ret);
 		}
 
+		ret = 0;
 		ops->retlen += iter.req.datalen;
 		ops->oobretlen += iter.req.ooblen;
 	}
@@ -670,16 +677,9 @@ static bool spinand_isbad(struct nand_device *nand, const struct nand_pos *pos)
 		.oobbuf.in = marker,
 		.mode = MTD_OPS_RAW,
 	};
-	int ret;
-
-	ret = spinand_select_target(spinand, pos->target);
-	if (ret)
-		return ret;
-
-	ret = spinand_read_page(spinand, &req, false);
-	if (ret)
-		return ret;
 
+	spinand_select_target(spinand, pos->target);
+	spinand_read_page(spinand, &req, false);
 	if (marker[0] != 0xff || marker[1] != 0xff)
 		return true;
 
@@ -723,6 +723,10 @@ static int spinand_markbad(struct nand_device *nand, const struct nand_pos *pos)
 	if (ret)
 		return ret;
 
+	ret = spinand_write_enable_op(spinand);
+	if (ret)
+		return ret;
+
 	return spinand_write_page(spinand, &req);
 }