mtd: mxc_nand: limit the size of used oob
For 4k pages the i.MX NFC hardware uses no more than 218 bytes for 8bit ECC
data. Larger oobsize confuses the logic of copy_spare(). Limit the size of used
oob size to avoid that.
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
index 5bbc1c5..ceeb61c 100644
--- a/drivers/mtd/nand/mxc_nand.c
+++ b/drivers/mtd/nand/mxc_nand.c
@@ -189,6 +189,7 @@
int clk_act;
int irq;
int eccsize;
+ int used_oobsize;
int active_cs;
struct completion op_completion;
@@ -827,7 +828,7 @@
u16 sparebuf_size = host->devtype_data->spare_len;
/* size of oob chunk for all but possibly the last one */
- oob_chunk_size = (mtd->oobsize / num_chunks) & ~1;
+ oob_chunk_size = (host->used_oobsize / num_chunks) & ~1;
if (bfrom) {
for (i = 0; i < num_chunks - 1; i++)
@@ -838,7 +839,7 @@
/* the last chunk */
memcpy32_fromio(d + i * oob_chunk_size,
s + i * sparebuf_size,
- mtd->oobsize - i * oob_chunk_size);
+ host->used_oobsize - i * oob_chunk_size);
} else {
for (i = 0; i < num_chunks - 1; i++)
memcpy32_toio(&s[i * sparebuf_size],
@@ -848,7 +849,7 @@
/* the last chunk */
memcpy32_toio(&s[oob_chunk_size * sparebuf_size],
&d[i * oob_chunk_size],
- mtd->oobsize - i * oob_chunk_size);
+ host->used_oobsize - i * oob_chunk_size);
}
}
@@ -1606,6 +1607,15 @@
else if (mtd->writesize == 4096)
this->ecc.layout = host->devtype_data->ecclayout_4k;
+ /*
+ * Experimentation shows that i.MX NFC can only handle up to 218 oob
+ * bytes. Limit used_oobsize to 218 so as to not confuse copy_spare()
+ * into copying invalid data to/from the spare IO buffer, as this
+ * might cause ECC data corruption when doing sub-page write to a
+ * partially written page.
+ */
+ host->used_oobsize = min(mtd->oobsize, 218U);
+
if (this->ecc.mode == NAND_ECC_HW) {
if (is_imx21_nfc(host) || is_imx27_nfc(host))
this->ecc.strength = 1;