mtd: de-select the chip when it is not used

When we scan several nand chips with nand_scan(), such as
     .......................
      nand_scan(*, 2);
     .......................

In nand_scan_ident(), the maxchips will become 2, so the current code
will select chip 1 to read the device ID. But the chip 0 is still
selected in this case.

To make the logic clear, we'd better de-select the chip when it is not used.

This patch de-select the nand chip if it is not used any more.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 01505406ca7b..95d56ed8500a 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -3329,6 +3329,8 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips,
                 return PTR_ERR(type);
         }
 
+        chip->select_chip(mtd, -1);
+
         /* Check for a chip array */
         for (i = 1; i < maxchips; i++) {
                 chip->select_chip(mtd, i);
@@ -3338,8 +3340,11 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips,
                 chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
                 /* Read manufacturer and device IDs */
                 if (nand_maf_id != chip->read_byte(mtd) ||
-                    nand_dev_id != chip->read_byte(mtd))
+                    nand_dev_id != chip->read_byte(mtd)) {
+                        chip->select_chip(mtd, -1);
                         break;
+                }
+                chip->select_chip(mtd, -1);
         }
         if (i > 1)
                 pr_info("%d NAND chips detected\n", i);
@@ -3598,9 +3603,6 @@ int nand_scan_tail(struct mtd_info *mtd)
         /* Initialize state */
         chip->state = FL_READY;
 
-        /* De-select the device */
-        chip->select_chip(mtd, -1);
-
         /* Invalidate the pagebuffer reference */
         chip->pagebuf = -1;