Commit ed8165c7 authored by Ben Dooks's avatar Ben Dooks Committed by David Woodhouse
Browse files

[MTD] [NAND] Verify probe by retrying to checking the results match 



With modern systems using bus-hold instead of bus pull-up, it can
often lead to erroneous reporting of NAND devices where there are
none. Do a double probe to ensure that the result we got the first
time is repeatable, and if it is not then return that there is no
chip there.

Signed-off-by: default avatarBen Dooks <ben-linux@fluff.org>
Signed-off-by: default avatarDavid Woodhouse <dwmw2@infradead.org>
parent 37e5ffa3

drivers/mtd/nand/nand_base.c

+21 −0
Original line number Diff line number Diff line
@@ -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) {

CRA Git | Maintained and supported by SUSTech CRA and CCSE