From: Boris Brezillon <boris.brezillon@free-electrons.com>
To: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Cc: dwmw2@infradead.org, computersforpeace@gmail.com,
marek.vasut@gmail.com, cyrille.pitchen@wedev4u.fr,
linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
Lars-Peter Clausen <lars@metafoo.de>
Subject: Re: [RFC] NAND: Optimize NAND_ECC_HW_OOB_FIRST read
Date: Mon, 30 Oct 2017 09:34:26 +0100 [thread overview]
Message-ID: <20171030093426.30827ef5@bbrezillon> (raw)
In-Reply-To: <20171028074351.13118-1-prasannatsmkumar@gmail.com>
Hi PrasannaKumar,
On Sat, 28 Oct 2017 13:13:51 +0530
PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com> wrote:
> From: Lars-Peter Clausen <lars@metafoo.de>
>
> Avoid sending unnecessary READ commands to the chip.
>
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
> Signed-off-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
> ---
> This patch is taken from git://projects.qi-hardware.com/qi-kernel.git
> branch jz-3.16. From [1] and [2] it can be seen that the patch author
> thinks this can be sent upstream but it never happened so far. This
> patch is used in OpenWRT as seen from [3].
Sounds reasonable, but it's likely to conflict with something I'd like
to queue for 4.16 [1]. I'll rebase this patch on nand/next once the
->exec_op() series is merged. Don't hesitate to ping me if I forget.
Regards,
Boris
[1]http://patchwork.ozlabs.org/project/linux-mtd/list/?series=8923
>
> I have only compile tested the patch.
>
> 1. https://www.mail-archive.com/discussion@lists.en.qi-hardware.com/msg04635.html
> 2. https://www.mail-archive.com/discussion@lists.en.qi-hardware.com/msg04639.html
> 3. https://git.lede-project.org/?p=source.git;a=blob;f=target/linux/xburst/patches-3.18/002-NAND-Optimize-NAND_ECC_HW_OOB_FIRST-read.patch;h=046da51912de3cd4444779df5de13d2c1999719a;hb=c03d4317a6bc891cb4a5e89cbdd77f37c23aff86
>
> drivers/mtd/nand/nand_base.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index 12edaae..4bf3bdb 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -1680,9 +1680,15 @@ static int nand_read_page_hwecc_oob_first(struct mtd_info *mtd,
> unsigned int max_bitflips = 0;
>
> /* Read the OOB area first */
> - chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page);
> - chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
> - chip->cmdfunc(mtd, NAND_CMD_READ0, 0, page);
> + if (mtd->writesize > 512) {
> + chip->cmdfunc(mtd, NAND_CMD_READ0, mtd->writesize, page);
> + chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
> + chip->cmdfunc(mtd, NAND_CMD_RNDOUT, 0, -1);
> + } else {
> + chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page);
> + chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
> + chip->cmdfunc(mtd, NAND_CMD_READ0, 0, page);
> + }
>
> ret = mtd_ooblayout_get_eccbytes(mtd, ecc_code, chip->oob_poi, 0,
> chip->ecc.total);
> @@ -1902,8 +1908,10 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
> __func__, buf);
>
> read_retry:
> - if (nand_standard_page_accessors(&chip->ecc))
> + if (nand_standard_page_accessors(&chip->ecc) &&
> + chip->ecc.mode != NAND_ECC_HW_OOB_FIRST) {
> chip->cmdfunc(mtd, NAND_CMD_READ0, 0x00, page);
> + }
>
> /*
> * Now read the page into the buffer. Absent an error,
next prev parent reply other threads:[~2017-10-30 8:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-28 7:43 [RFC] NAND: Optimize NAND_ECC_HW_OOB_FIRST read PrasannaKumar Muralidharan
2017-10-30 8:34 ` Boris Brezillon [this message]
2017-10-30 12:47 ` PrasannaKumar Muralidharan
2017-10-30 13:03 ` Boris Brezillon
2017-10-30 13:34 ` PrasannaKumar Muralidharan
2017-10-31 16:20 ` PrasannaKumar Muralidharan
2018-01-27 7:42 ` PrasannaKumar Muralidharan
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