[PATCH v2] mtd: rawnand: sunxi: fit maximized ECC step to page size

[James Hilliard <james.hilliard1@gmail.com>]

When nand-ecc-maximize is set, the driver unconditionally selects a
1024-byte ECC step. A NAND with a 512-byte page consequently produces
zero ECC steps before the available OOB bytes are divided by the step
count.

The older sunxi NAND controllers support 512-byte ECC blocks. Select the
smaller of the page size and the preferred 1024-byte step, using a
512-byte step for a 512-byte page while retaining 1024-byte steps for
larger pages. Unsupported smaller steps and controllers without
512-byte support continue to be rejected by the existing checks.

Fixes: 4796d8655915 ("mtd: nand: sunxi: Support ECC maximization")
Cc: stable@vger.kernel.org
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
---
Changes in v2:
- fix ECC maximization at its source by selecting a 512-byte step for
  512-byte pages instead of validating the derived step count
- retain 1024-byte steps for larger pages and the existing capability checks
- rebase on the current MTD nand/next branch
- Link to v1: https://patch.msgid.link/20260811060651.227431-1-james.hilliard1@gmail.com
---
 drivers/mtd/nand/raw/sunxi_nand.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/raw/sunxi_nand.c b/drivers/mtd/nand/raw/sunxi_nand.c
index 83666dd6cb2a..de1e6b49f79a 100644
--- a/drivers/mtd/nand/raw/sunxi_nand.c
+++ b/drivers/mtd/nand/raw/sunxi_nand.c
@@ -2084,7 +2084,7 @@ static int sunxi_nand_hw_ecc_ctrl_init(struct nand_chip *nand,
 	if (nanddev->ecc.user_conf.flags & NAND_ECC_MAXIMIZE_STRENGTH) {
 		int bytes = mtd->oobsize;
 
-		ecc->size = 1024;
+		ecc->size = min_t(unsigned int, mtd->writesize, 1024);
 		nsectors = mtd->writesize / ecc->size;
 
 		if (!nfc->caps->reg_user_data_len) {

---
base-commit: def559a215699aa2f2d8ef98f30156b9d562a154
change-id: 20260904-submit-sunxi-nand-ecc-step-validation-0e571088b5e7

Best regards,
--  
James Hilliard <james.hilliard1@gmail.com>