@@ -486,6 +486,33 @@ static uint8_t bch_erase_block(struct nandi_controller *nandi,
}
/*
+ * Detect an erased page, tolerating and correcting up to a specified number of
+ * bits at '0'. (For many devices, it is now deemed within spec for an erased
+ * page to include a number of bits at '0', either as a result of read-disturb
+ * behaviour or 'stuck-at-zero' failures.) Returns the number of corrected
+ * bits, or a '-1' if we have exceeded the maximum number of bits at '0' (likely
+ * to be a genuine uncorrectable ECC error). In the latter case, the data must
+ * be returned unmodified, in accordance with the MTD API.
+ */
+static int check_erased_page(uint8_t *data, uint32_t page_size, int max_zeros)
+{
+ uint8_t *b = data;
+ int zeros = 0;
+ int i;
+
+ for (i = 0; i < page_size; i++) {
+ zeros += hweight8(~*b++);
+ if (zeros > max_zeros)
+ return -1;
+ }
+
+ if (zeros)
+ memset(data, 0xff, page_size);
+
+ return zeros;
+}
+
+/*
* Initialisation
*/
static int bch_check_compatibility(struct nandi_controller *nandi,
Detect an erased page, tolerating and correcting up to a specified number of bits at '0'. Downgrade uncorrectable ECC error for an erased page, tolerating 'sectors_per_page' bits at '0'. Signed-off-by: Lee Jones <lee.jones@linaro.org> --- drivers/mtd/nand/stm_nand_bch.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+)