NAND: Scan bad blocks lazily.

Rather than scanning on boot, scan upon the first attempt to check the
badness of a block.  This speeds up boot when not using NAND, and reduces
the likelihood of needing to reflash via JTAG if NAND becomes
nonfunctional.

Signed-off-by: Ilya Yanok <yanok@emcraft.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 7bceea8ac3d893cab623e2aaa80d4e3fee74698b..cf2f3745542b7ceae4626fe2b41e7524c3d0f77e 100644 (file)
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -457,6 +457,11 @@ static int nand_block_checkbad(struct mtd_info *mtd, loff_t ofs, int getchip,
 {
        struct nand_chip *chip = mtd->priv;
 
+       if (!(chip->options & NAND_BBT_SCANNED)) {
+               chip->scan_bbt(mtd);
+               chip->options |= NAND_BBT_SCANNED;
+       }
+
        if (!chip->bbt)
                return chip->block_bad(mtd, ofs, getchip);
 
@@ -2721,10 +2726,9 @@ int nand_scan_tail(struct mtd_info *mtd)
 
        /* Check, if we should skip the bad block table scan */
        if (chip->options & NAND_SKIP_BBTSCAN)
-               return 0;
+               chip->options |= NAND_BBT_SCANNED;
 
-       /* Build bad block table */
-       return chip->scan_bbt(mtd);
+       return 0;
 }
 
 /* module_text_address() isn't exported, and it's mostly a pointless

diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index f9b7d36a73a027df6abbc768418d7b760ef1badd..2993a89e1b3cdae4995f0dce5d587f59e3b28ca0 100644 (file)
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -204,6 +204,8 @@ typedef enum {
    (e.g. because it needs them DMA-coherent */
 #define NAND_OWN_BUFFERS       0x00040000
 /* Options set by nand scan */
+/* bbt has already been read */
+#define NAND_BBT_SCANNED       0x40000000
 /* Nand scan has allocated controller struct */
 #define NAND_CONTROLLER_ALLOC  0x80000000