[PATCH v4 1/3] mtd: rawnand: rockchip: fix oobfree offset and description

Johan Jonker
2023-07-10T12:42:26Z

Rockchip boot blocks are written per 4 x 512 byte sectors per page.
Each page with boot blocks must have a page address (PA) pointer in OOB
to the next page.

The currently advertised free OOB area starts at offset 6, like
if 4 PA bytes were located right after the BBM. This is wrong as the
PA bytes are located right before the ECC bytes.

Fix the layout by allowing access to all bytes between the BBM and the
PA bytes instead of reserving 4 bytes right after the BBM.

This change breaks existing jffs2 users.

Fixes: 058e0e847d54 ("mtd: rawnand: rockchip: NFC driver for RK3308, RK2928 and others")
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
---

Changed V4:
Reduce subject size
Add 'Fixes:' tag
Reword

Changed V3:
Change prefixes
Reword
State break existing users.

---

Example:

Wrong free OOB offset starts at OOB6:
oob_region->offset = NFC_SYS_DATA_SIZE + 2;
= 4 + 2
= 6

oob_region->length = rknand->metadata_size - NFC_SYS_DATA_SIZE - 2;
= 32 - 4 - 2
= 26

Together with this length above it overlaps a reserved space for the
boot blocks Page Address(PA)

chip->oob_poi buffer layout for 8 steps:

BBM0 BBM1 OOB2 OOB3 | OOB4 OOB5 OOB6 OOB7

OOB8 OOB9 OOB10 OOB11 | OOB12 OOB13 OOB15 OOB15
OOB16 OOB17 OOB18 OOB19 | OOB20 OOB21 OOB22 OOB23

OOB24 OOB25 OOB26 OOB27 | PA0 PA1 PA2 PA3

ECC0 ECC1 ECC2 ECC3 | ... ... ... ...

Fix by new offset at OOB2:
oob_region->offset = 2;

The full range of free OOB with 8 steps runs from OOB2
till/including OOB27.
---
drivers/mtd/nand/raw/rockchip-nand-controller.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/mtd/nand/raw/rockchip-nand-controller.c b/drivers/mtd/nand/raw/rockchip-nand-controller.c
index 2312e27362cb..37fc07ba57aa 100644
--- a/drivers/mtd/nand/raw/rockchip-nand-controller.c
+++ b/drivers/mtd/nand/raw/rockchip-nand-controller.c
@@ -562,9 +562,10 @@ static int rk_nfc_write_page_raw(struct nand_chip *chip, const u8 *buf,
* BBM OOB1 OOB2 OOB3 |......| PA0 PA1 PA2 PA3
*
* The rk_nfc_ooblayout_free() function already has reserved
- * these 4 bytes with:
+ * these 4 bytes together with 2 bytes for BBM
+ * by reducing it's length:
*
- * oob_region->offset = NFC_SYS_DATA_SIZE + 2;
+ * oob_region->length = rknand->metadata_size - NFC_SYS_DATA_SIZE - 2;
*/
if (!i)
memcpy(rk_nfc_oob_ptr(chip, i),
@@ -933,12 +934,8 @@ static int rk_nfc_ooblayout_free(struct mtd_info *mtd, int section,
if (section)
return -ERANGE;

- /*
- * The beginning of the OOB area stores the reserved data for the NFC,
- * the size of the reserved data is NFC_SYS_DATA_SIZE bytes.
- */
oob_region->length = rknand->metadata_size - NFC_SYS_DATA_SIZE - 2;
- oob_region->offset = NFC_SYS_DATA_SIZE + 2;
+ oob_region->offset = 2;

return 0;
}