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Groups > linux.kernel > #1659722

[PATCH v5 20/23] mtd: nand: denali: support hardware-assisted erased page detection

From Masahiro Yamada <yamada.masahiro@socionext.com>
Newsgroups linux.kernel
Subject [PATCH v5 20/23] mtd: nand: denali: support hardware-assisted erased page detection
Date 2017-06-07 14:00 +0200
Message-ID <tPHN1-68d-47@gated-at.bofh.it> (permalink)
References <tPHMZ-68d-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Recent versions of this IP support automatic erased page detection.
If an erased page is detected on reads, the controller does not set
INTR__ECC_UNCOR_ERR, but INTR__ERASED_PAGE.

The detection of erased page is based on the number of zeros in a
page; if the number of zeros is less than the value in the field
ERASED_THRESHOLD, the page is assumed as erased.

Please note ERASED_THRESHOLD specifies the number of zeros in a _page_
instead of an ECC chunk.  Moreover, the controller does not provide a
way to know the actual number of bitflips.

Actually, an erased page (all 0xff) is not an ECC correctable pattern
on the Denali ECC engine.  In other words, there is overlap between
the following two:

[1] a bit pattern reachable from a valid payload + ECC pattern within
    ecc.strength bitflips
[2] a bit pattern reachable from an erased state (all 0xff) within
    ecc.strength bitflips

So, this feature may intercept ECC correctable patterns, then replace
[1] with [2].

After all, this feature can work safely only when ECC_THRESHOLD == 1,
i.e. detect erased pages without any bitflips.  This should be the
case most of the time.  If there are some bitflips, the driver will
fallback to the software method by using nand_check_erased_ecc_chunk().

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

Changes in v5:
  - Set ECC_THRESHOLD to 1

Changes in v4: None
Changes in v3: None
Changes in v2:
  - Newly added

 drivers/mtd/nand/denali.c | 3 ++-
 drivers/mtd/nand/denali.h | 5 +++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
index dcadf9655d7a..90c702b9f14c 100644
--- a/drivers/mtd/nand/denali.c
+++ b/drivers/mtd/nand/denali.c
@@ -1446,7 +1446,8 @@ int denali_init(struct denali_nand_info *denali)
 		"chosen ECC settings: step=%d, strength=%d, bytes=%d\n",
 		chip->ecc.size, chip->ecc.strength, chip->ecc.bytes);
 
-	iowrite32(chip->ecc.strength, denali->flash_reg + ECC_CORRECTION);
+	iowrite32(MAKE_ECC_CORRECTION(chip->ecc.strength, 1),
+		  denali->flash_reg + ECC_CORRECTION);
 	iowrite32(mtd->erasesize / mtd->writesize,
 		  denali->flash_reg + PAGES_PER_BLOCK);
 	iowrite32(chip->options & NAND_BUSWIDTH_16 ? 1 : 0,
diff --git a/drivers/mtd/nand/denali.h b/drivers/mtd/nand/denali.h
index f5da52f09e34..657a794af695 100644
--- a/drivers/mtd/nand/denali.h
+++ b/drivers/mtd/nand/denali.h
@@ -110,6 +110,10 @@
 
 #define ECC_CORRECTION				0x1b0
 #define     ECC_CORRECTION__VALUE			GENMASK(4, 0)
+#define     ECC_CORRECTION__ERASE_THRESHOLD		GENMASK(31, 16)
+#define     MAKE_ECC_CORRECTION(val, thresh)		\
+			(((val) & (ECC_CORRECTION__VALUE)) | \
+			(((thresh) << 16) & (ECC_CORRECTION__ERASE_THRESHOLD)))
 
 #define READ_MODE				0x1c0
 #define     READ_MODE__VALUE				GENMASK(3, 0)
@@ -233,6 +237,7 @@
 #define     INTR__RST_COMP				BIT(13)
 #define     INTR__PIPE_CMD_ERR				BIT(14)
 #define     INTR__PAGE_XFER_INC				BIT(15)
+#define     INTR__ERASED_PAGE				BIT(16)
 
 #define PAGE_CNT(bank)				(0x430 + (bank) * 0x50)
 #define ERR_PAGE_ADDR(bank)			(0x440 + (bank) * 0x50)
-- 
2.7.4

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Thread

[PATCH v5 00/23] mtd: nand: denali: Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 22/23] mtd: nand: denali: use non-managed kmalloc() for DMA buffer Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 15/23] mtd: nand: denali: use interrupt instead of polling for bank reset Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 16/23] mtd: nand: denali: propagate page to helpers via function argument Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 18/23] mtd: nand: denali: use flag instead of register macro for direction Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 21/23] mtd: nand: denali: skip driver internal bounce buffer when possible Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 11/23] mtd: nand: denali: fix NAND_CMD_STATUS handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 19/23] mtd: nand: denali: fix raw and oob accessors for syndrome page layout Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
    Re: [PATCH v5 19/23] mtd: nand: denali: fix raw and oob accessors  for syndrome page layout Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-07 16:10 +0200
      Re: [PATCH v5 19/23] mtd: nand: denali: fix raw and oob accessors for  syndrome page layout Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-08 13:30 +0200
        Re: [PATCH v5 19/23] mtd: nand: denali: fix raw and oob accessors for  syndrome page layout Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 06:50 +0200
  [PATCH v5 09/23] mtd: nand: denali: handle timing parameters by setup_data_interface() Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 14/23] mtd: nand: denali: fix bank reset function to detect the number of chips Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 12/23] mtd: nand: denali: fix NAND_CMD_PARAM handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 17/23] mtd: nand: denali: merge struct nand_buf into struct denali_nand_info Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 06/23] mtd: nand: denali: set NAND_ECC_CUSTOM_PAGE_ACCESS Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
    Re: [PATCH v5 06/23] mtd: nand: denali: set  NAND_ECC_CUSTOM_PAGE_ACCESS Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-07 15:30 +0200
      Re: [PATCH v5 06/23] mtd: nand: denali: set NAND_ECC_CUSTOM_PAGE_ACCESS Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-08 09:40 +0200
  [PATCH v5 05/23] mtd: nand: denali_dt: add compatible strings for UniPhier SoC variants Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
    Re: [PATCH v5 05/23] mtd: nand: denali_dt: add compatible strings  for UniPhier SoC variants Rob Herring <robh@kernel.org> - 2017-06-07 21:10 +0200
  [PATCH v5 23/23] mtd: nand: denali: enable bad block table scan Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 01/23] mtd: nand: add generic helpers to check, match, maximize ECC settings Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 20/23] mtd: nand: denali: support hardware-assisted erased page detection Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 10/23] mtd: nand: denali: rework interrupt handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
    Re: [PATCH v5 10/23] mtd: nand: denali: rework interrupt handling Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-07 16:00 +0200
      Re: [PATCH v5 10/23] mtd: nand: denali: rework interrupt handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-08 08:20 +0200
        Re: [PATCH v5 10/23] mtd: nand: denali: rework interrupt handling Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-08 09:20 +0200
          Re: [PATCH v5 10/23] mtd: nand: denali: rework interrupt handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-08 12:50 +0200
            Re: [PATCH v5 10/23] mtd: nand: denali: rework interrupt handling Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-08 13:30 +0200
              Re: [PATCH v5 10/23] mtd: nand: denali: rework interrupt handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-08 15:00 +0200
                Re: [PATCH v5 10/23] mtd: nand: denali: rework interrupt handling Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-08 17:50 +0200
                Re: [PATCH v5 10/23] mtd: nand: denali: rework interrupt handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-08 19:30 +0200
                Re: [PATCH v5 10/23] mtd: nand: denali: rework interrupt handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-08 19:40 +0200
                Re: [PATCH v5 10/23] mtd: nand: denali: rework interrupt handling Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-09 10:00 +0200
                Re: [PATCH v5 10/23] mtd: nand: denali: rework interrupt handling Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-13 06:50 +0200
  [PATCH v5 04/23] mtd: nand: denali: remove Toshiba and Hynix specific fixup code Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 13/23] mtd: nand: denali: switch over to cmd_ctrl instead of cmdfunc Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:00 +0200
  [PATCH v5 02/23] mtd: nand: add a shorthand to generate nand_ecc_caps structure Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:10 +0200
  [PATCH v5 03/23] mtd: nand: denali: avoid hard-coding ECC step, strength, bytes Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:10 +0200
  [PATCH v5 07/23] mtd: nand: denali: do not propagate NAND_STATUS_FAIL to waitfunc() Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-07 14:10 +0200
    Re: [PATCH v5 07/23] mtd: nand: denali: do not propagate  NAND_STATUS_FAIL to waitfunc() Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-07 15:40 +0200
      Re: [PATCH v5 07/23] mtd: nand: denali: do not propagate  NAND_STATUS_FAIL to waitfunc() Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-08 08:20 +0200
        Re: [PATCH v5 07/23] mtd: nand: denali: do not propagate  NAND_STATUS_FAIL to waitfunc() Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-08 09:10 +0200
          Re: [PATCH v5 07/23] mtd: nand: denali: do not propagate  NAND_STATUS_FAIL to waitfunc() Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-08 11:50 +0200
            Re: [PATCH v5 07/23] mtd: nand: denali: do not propagate  NAND_STATUS_FAIL to waitfunc() Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-08 12:10 +0200
  Re: [PATCH v5 00/23] mtd: nand: denali: Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-08 08:20 +0200
    Re: [PATCH v5 00/23] mtd: nand: denali: Denali NAND IP patch bomb Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-08 09:20 +0200
    Re: [PATCH v5 00/23] mtd: nand: denali: Denali NAND IP patch bomb Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-08 09:20 +0200
      Re: [PATCH v5 00/23] mtd: nand: denali: Denali NAND IP patch bomb Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-08 09:20 +0200
      Re: [PATCH v5 00/23] mtd: nand: denali: Denali NAND IP patch bomb Boris Brezillon <boris.brezillon@free-electrons.com> - 2017-06-11 22:20 +0200

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