[PATCH] nand: fix repeated BBT writes due to missing OOB read

[Rafal Vonau]

During system startup, U-Boot overwrites the Bad Block Table (BBT) on NAND
flash
every time because it fails to properly read the existing BBT. This happens
due
to missing OOB (Out-Of-Band) reads when checking for the BBT signature.

As a result, U-Boot assumes the BBT is invalid or missing and rewrites it on
every boot, causing unnecessary NAND wear and slower startup.

This patch corrects the issue by enabling proper reading of the BBT from the
OOB area, preventing redundant writes.

Signed-off-by: Rafal Vonau <rafal.vonau at gmail.com>
---
drivers/mtd/nand/raw/zynq_nand.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/drivers/mtd/nand/raw/zynq_nand.c
b/drivers/mtd/nand/raw/zynq_nand.c
index ca1aff25a52..3adacb1b46c 100644
--- a/drivers/mtd/nand/raw/zynq_nand.c
+++ b/drivers/mtd/nand/raw/zynq_nand.c
@@ -522,6 +522,20 @@ static int zynq_nand_read_page_raw_nooob(struct
mtd_info *mtd,
               struct nand_chip *chip, u8 *buf, int oob_required, int page)
{
       chip->read_buf(mtd, buf, mtd->writesize);
+
+       if (oob_required) {
+               unsigned long data_width = 4;
+               unsigned long data_phase_addr = 0;
+               u8 *p = chip->oob_poi;
+               chip->read_buf(mtd, p, (mtd->oobsize - data_width));
+               p += (mtd->oobsize - data_width);
+
+               data_phase_addr = (unsigned long)chip->IO_ADDR_R;
+               data_phase_addr |= ZYNQ_NAND_CLEAR_CS;
+               chip->IO_ADDR_R = (void __iomem *)data_phase_addr;
+               chip->read_buf(mtd, p, data_width);
+       }
+
       return 0;
}

--
2.20.1
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