mtd: de-select the chip when it is not used
Huang Shijie [Fri, 9 Nov 2012 08:23:45 +0000 (16:23 +0800)]
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>

drivers/mtd/nand/nand_base.c

index 0150540..95d56ed 100644 (file)
@@ -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;