[3.5.y.z extended stable] Patch "mtd: nand: hack ONFI for non-power-of-2 dimensions" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Fri Nov 29 14:02:23 UTC 2013

This is a note to let you know that I have just added a patch titled

    mtd: nand: hack ONFI for non-power-of-2 dimensions

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



>From 28c56bc57d36650fecd90e352578d526837e643a Mon Sep 17 00:00:00 2001
From: Brian Norris <computersforpeace at gmail.com>
Date: Tue, 27 Aug 2013 18:45:10 -0700
Subject: mtd: nand: hack ONFI for non-power-of-2 dimensions

commit 4355b70cf48363c50a9de450b01178c83aba8f6a upstream.

Some bright specification writers decided to write this in the ONFI spec
(from ONFI 3.0, Section 3.1):

  "The number of blocks and number of pages per block is not required to
  be a power of two. In the case where one of these values is not a
  power of two, the corresponding address shall be rounded to an
  integral number of bits such that it addresses a range up to the
  subsequent power of two value. The host shall not access upper
  addresses in a range that is shown as not supported."

This breaks every assumption MTD makes about NAND block/chip-size
dimensions -- they *must* be a power of two!

And of course, an enterprising manufacturer has made use of this lovely
freedom. Exhibit A: Micron MT29F32G08CBADAWP

  "- Plane size: 2 planes x 1064 blocks per plane
   - Device size: 32Gb: 2128 blockss [sic]"

This quickly hits a BUG() in nand_base.c, since the extra dimensions
overflow so we think it's a second chip (on my single-chip setup):

    ONFI param page 0 valid
    ONFI flash detected
    NAND device: Manufacturer ID: 0x2c, Chip ID: 0x44 (Micron MT29F32G08CBADAWP), 4256MiB, page size: 8192, OOB size: 744
    ------------[ cut here ]------------
    kernel BUG at drivers/mtd/nand/nand_base.c:203!
    Internal error: Oops - BUG: 0 [#1] SMP ARM
    [... trim ...]
    [<c02cf3e4>] (nand_select_chip+0x18/0x2c) from [<c02d25c0>] (nand_do_read_ops+0x90/0x424)
    [<c02d25c0>] (nand_do_read_ops+0x90/0x424) from [<c02d2dd8>] (nand_read+0x54/0x78)
    [<c02d2dd8>] (nand_read+0x54/0x78) from [<c02ad2c8>] (mtd_read+0x84/0xbc)
    [<c02ad2c8>] (mtd_read+0x84/0xbc) from [<c02d4b28>] (scan_read.clone.4+0x4c/0x64)
    [<c02d4b28>] (scan_read.clone.4+0x4c/0x64) from [<c02d4c88>] (search_bbt+0x148/0x290)
    [<c02d4c88>] (search_bbt+0x148/0x290) from [<c02d4ea4>] (nand_scan_bbt+0xd4/0x5c0)
    [... trim ...]
    ---[ end trace 0c9363860d865ff2 ]---

So to fix this, just truncate these dimensions down to the greatest
power-of-2 dimension that is less than or equal to the specified

Signed-off-by: Brian Norris <computersforpeace at gmail.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 drivers/mtd/nand/nand_base.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index c429abd..09d0cea 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2905,10 +2905,21 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,
 	sanitize_string(p->model, sizeof(p->model));
 	if (!mtd->name)
 		mtd->name = p->model;
 	mtd->writesize = le32_to_cpu(p->byte_per_page);
-	mtd->erasesize = le32_to_cpu(p->pages_per_block) * mtd->writesize;
+	/*
+	 * pages_per_block and blocks_per_lun may not be a power-of-2 size
+	 * (don't ask me who thought of this...). MTD assumes that these
+	 * dimensions will be power-of-2, so just truncate the remaining area.
+	 */
+	mtd->erasesize = 1 << (fls(le32_to_cpu(p->pages_per_block)) - 1);
+	mtd->erasesize *= mtd->writesize;
 	mtd->oobsize = le16_to_cpu(p->spare_bytes_per_page);
-	chip->chipsize = le32_to_cpu(p->blocks_per_lun);
+	/* See erasesize comment */
+	chip->chipsize = 1 << (fls(le32_to_cpu(p->blocks_per_lun)) - 1);
 	chip->chipsize *= (uint64_t)mtd->erasesize * p->lun_count;
 	*busw = 0;
 	if (le16_to_cpu(p->features) & 1)

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