linux-kernel - [RESEND PATCH v2 0/3] mtd: use ONFI bad blocks per LUN to calculate UBI bad PEB limit

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Message-ID: <1477595642-11454-1-git-send-email-zach.brown@ni.com>
Date:   Thu, 27 Oct 2016 14:13:59 -0500
From:   Zach Brown <zach.brown@...com>
To:     <dwmw2@...radead.org>
CC:     <computersforpeace@...il.com>,
        <boris.brezillon@...e-electrons.com>, <richard@....at>,
        <dedekind1@...il.com>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [RESEND PATCH v2 0/3] mtd: use ONFI bad blocks per LUN to calculate UBI bad PEB limit

For ONFI-compliant NAND devices, the ONFI parameters report the maximum number
of bad blocks per LUN that will be encountered over the lifetime of the device,
so we can use that information to get a more accurate (and smaller) value for
the UBI bad PEB limit.

The ONFI parameter "maxiumum number of bad blocks per LUN" is the max number of
bad blocks that each individual LUN will ever ecounter. It is not the number of
bad blocks to reserve for the nand device per LUN in the device.

This means that in the worst case a UBI device spanning X LUNs will encounter
"maximum number of bad blocks per LUN" * X bad blocks. The implementation in
this patch assumes this worst case and allocates bad block accordingly.

These patches are ordered in terms of their dependencies, but ideally, all 3
would need to be applied for this to work as intended.

v1:
 * Changed commit message to address concerns from v1[1] about this patch set
   making best case assumptions.

[1]
http://lkml.iu.edu/hypermail/linux/kernel/1505.1/04822.html

Jeff Westfahl (3):
  mtd: introduce function max_bad_blocks
  mtd: nand: implement 'max_bad_blocks' mtd function
  mtd: ubi: use 'max_bad_blocks' to compute bad_peb_limit if available

 drivers/mtd/mtdpart.c        | 12 ++++++++++++
 drivers/mtd/nand/nand_base.c | 34 ++++++++++++++++++++++++++++++++++
 drivers/mtd/ubi/build.c      |  9 +++++++++
 include/linux/mtd/mtd.h      |  1 +
 4 files changed, 56 insertions(+)

-- 
2.7.4