X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=drivers%2Fmtd%2Fnand%2Fnand_base.c;h=ba1bdf787323190377c20aa239317ee278769b5b;hb=6c9fcaf2eec1b9f85226a694230dd957dd7926b3;hp=ddd4fc019042ff72250c887944a3410ec6b69459;hpb=c64768a7d671bcde80bca2aed93f9e07edc069c3;p=linux-2.6

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index ddd4fc0190..ba1bdf7873 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2229,6 +2229,7 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
 {
 	struct nand_flash_dev *type = NULL;
 	int i, dev_id, maf_idx;
+	int tmp_id, tmp_manf;
 
 	/* Select the device */
 	chip->select_chip(mtd, 0);
@@ -2240,6 +2241,26 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
 	*maf_id = chip->read_byte(mtd);
 	dev_id = chip->read_byte(mtd);
 
+	/* Try again to make sure, as some systems the bus-hold or other
+	 * interface concerns can cause random data which looks like a
+	 * possibly credible NAND flash to appear. If the two results do
+	 * not match, ignore the device completely.
+	 */
+
+	chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
+
+	/* Read manufacturer and device IDs */
+
+	tmp_manf = chip->read_byte(mtd);
+	tmp_id = chip->read_byte(mtd);
+
+	if (tmp_manf != *maf_id || tmp_id != dev_id) {
+		printk(KERN_INFO "%s: second ID read did not match "
+		       "%02x,%02x against %02x,%02x\n", __func__,
+		       *maf_id, dev_id, tmp_manf, tmp_id);
+		return ERR_PTR(-ENODEV);
+	}
+
 	/* Lookup the flash id */
 	for (i = 0; nand_flash_ids[i].name != NULL; i++) {
 		if (dev_id == nand_flash_ids[i].id) {
@@ -2469,8 +2490,12 @@ int nand_scan_tail(struct mtd_info *mtd)
 			chip->ecc.write_oob = nand_write_oob_std;
 
 	case NAND_ECC_HW_SYNDROME:
-		if (!chip->ecc.calculate || !chip->ecc.correct ||
-		    !chip->ecc.hwctl) {
+		if ((!chip->ecc.calculate || !chip->ecc.correct ||
+		     !chip->ecc.hwctl) &&
+		    (!chip->ecc.read_page ||
+		     chip->ecc.read_page == nand_read_page_hwecc ||
+		     !chip->ecc.write_page ||
+		     chip->ecc.write_page == nand_write_page_hwecc)) {
 			printk(KERN_WARNING "No ECC functions supplied, "
 			       "Hardware ECC not possible\n");
 			BUG();