diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 380f783..fd5c307 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2862,6 +2862,65 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,
 }
 
 /*
+ * nand_id_has_period - Check if an ID string has a given wraparound period
+ * @id_data: the ID string
+ * @arrlen: the length of the @id_data array
+ * @period: the period of repitition
+ *
+ * Check if an ID string is repeated within a given sequence of bytes at
+ * specific repetition interval period (e.g., {0x20,0x01,0x7F,0x20} has a
+ * period of 2). This is a helper function for nand_id_len(). Returns non-zero
+ * if the repetition has a period of @period; otherwise, returns zero.
+ */
+static int nand_id_has_period(u8 *id_data, int arrlen, int period)
+{
+	int i, j;
+	for (i = 0; i < period; i++)
+		for (j = i + period; j < arrlen; j += period)
+			if (id_data[i] != id_data[j])
+				return 0;
+	return 1;
+}
+
+/*
+ * nand_id_len - Get the length of an ID string returned by CMD_READID
+ * @id_data: the ID string
+ * @arrlen: the length of the @id_data array
+
+ * Returns the length of the ID string, according to known wraparound/trailing
+ * zero patterns. If no pattern exists, returns the length of the array.
+ */
+static int nand_id_len(u8 *id_data, int arrlen)
+{
+	int last_nonzero, period;
+
+	/* Find last non-zero byte */
+	for (last_nonzero = arrlen - 1; last_nonzero >= 0; last_nonzero--)
+		if (id_data[last_nonzero])
+			break;
+
+	/* All zeros */
+	if (last_nonzero < 0)
+		return 0;
+
+	/* Calculate wraparound period */
+	for (period = 1; period < arrlen; period++)
+		if (nand_id_has_period(id_data, arrlen, period))
+			break;
+
+	/* There's a repeated pattern */
+	if (period < arrlen)
+		return period;
+
+	/* There are trailing zeros */
+	if (last_nonzero < arrlen - 1)
+		return last_nonzero + 1;
+
+	/* No pattern detected */
+	return arrlen;
+}
+
+/*
  * Many new NAND share similar device ID codes, which represent the size of the
  * chip. The rest of the parameters must be decoded according to generic or
  * manufacturer-specific "extended ID" decoding patterns.
@@ -2869,24 +2928,23 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,
 static void nand_decode_ext_id(struct mtd_info *mtd, struct nand_chip *chip,
 				u8 id_data[8], int *busw)
 {
-	int extid;
+	int extid, id_len;
 	/* The 3rd id byte holds MLC / multichip data */
 	chip->cellinfo = id_data[2];
 	/* The 4th id byte is the important one */
 	extid = id_data[3];
 
+	id_len = nand_id_len(id_data, 8);
+
 	/*
 	 * Field definitions are in the following datasheets:
 	 * Old style (4,5 byte ID): Samsung K9GAG08U0M (p.32)
 	 * New style   (6 byte ID): Samsung K9GBG08U0M (p.40)
 	 *
-	 * Check for wraparound + Samsung ID + nonzero 6th byte
-	 * to decide what to do.
+	 * Check for ID length + Samsung ID to decide what to do.
 	 */
-	if (id_data[0] == id_data[6] && id_data[1] == id_data[7] &&
-			id_data[0] == NAND_MFR_SAMSUNG &&
-			(chip->cellinfo & NAND_CI_CELLTYPE_MSK) &&
-			id_data[5] != 0x00) {
+	if (id_len == 6 && id_data[0] == NAND_MFR_SAMSUNG &&
+			(chip->cellinfo & NAND_CI_CELLTYPE_MSK)) {
 		/* Calc pagesize */
 		mtd->writesize = 2048 << (extid & 0x03);
 		extid >>= 2;