aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorBen Dooks <ben-linux@fluff.org>2008-04-14 09:58:58 -0400
committerDavid Woodhouse <dwmw2@infradead.org>2008-04-22 16:43:06 -0400
commited8165c75e3dd0b2e51b92a858cabe29ba00c9cb (patch)
treef024e77b2449f7308b6453f70ee293c7e633697a
parent37e5ffa3f15bd9a8b133ab13e9bef833b5eb33d4 (diff)
[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: Ben Dooks <ben-linux@fluff.org> Signed-off-by: David Woodhouse <dwmw2@infradead.org>
-rw-r--r--drivers/mtd/nand/nand_base.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 7acb1a0e7409..ba1bdf787323 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,
2229{ 2229{
2230 struct nand_flash_dev *type = NULL; 2230 struct nand_flash_dev *type = NULL;
2231 int i, dev_id, maf_idx; 2231 int i, dev_id, maf_idx;
2232 int tmp_id, tmp_manf;
2232 2233
2233 /* Select the device */ 2234 /* Select the device */
2234 chip->select_chip(mtd, 0); 2235 chip->select_chip(mtd, 0);
@@ -2240,6 +2241,26 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
2240 *maf_id = chip->read_byte(mtd); 2241 *maf_id = chip->read_byte(mtd);
2241 dev_id = chip->read_byte(mtd); 2242 dev_id = chip->read_byte(mtd);
2242 2243
2244 /* Try again to make sure, as some systems the bus-hold or other
2245 * interface concerns can cause random data which looks like a
2246 * possibly credible NAND flash to appear. If the two results do
2247 * not match, ignore the device completely.
2248 */
2249
2250 chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
2251
2252 /* Read manufacturer and device IDs */
2253
2254 tmp_manf = chip->read_byte(mtd);
2255 tmp_id = chip->read_byte(mtd);
2256
2257 if (tmp_manf != *maf_id || tmp_id != dev_id) {
2258 printk(KERN_INFO "%s: second ID read did not match "
2259 "%02x,%02x against %02x,%02x\n", __func__,
2260 *maf_id, dev_id, tmp_manf, tmp_id);
2261 return ERR_PTR(-ENODEV);
2262 }
2263
2243 /* Lookup the flash id */ 2264 /* Lookup the flash id */
2244 for (i = 0; nand_flash_ids[i].name != NULL; i++) { 2265 for (i = 0; nand_flash_ids[i].name != NULL; i++) {
2245 if (dev_id == nand_flash_ids[i].id) { 2266 if (dev_id == nand_flash_ids[i].id) {