[RFC] mtd: nand: Add a STATUS CMD after write verification

[RFC] mtd: nand: Add a STATUS CMD after write verification

[Bastian Hecht]

When using CONFIG_MTD_NAND_VERIFY_WRITE=y an extra read command is sent
to the NAND chip after writing a page. We need an extra status command
to avoid hick-ups that lead to page write failures.
---

Hello all,

I'm experiencing problems with my current setup and
CONFIG_MTD_NAND_VERIFY_WRITE=y. Usually the command sequence is like
0x70 		Status read
0x80 0x10 	Page prog
0x70
0x80 0x10 	Page prog
0x70
...

When activating write verification there is a read command before the
page prog.
0x80 0x10
0x70
0x0		read
0x80 0x10
0x70
...
This makes my chip write garbage, while the patch fixes it.
Now I wonder if this problem is caused by my NAND chip only, or if this
is a general problem that should be adressed.
---
 drivers/mtd/nand/nand_base.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 8a393f9..62d6691 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2101,6 +2101,8 @@ static int nand_write_page(struct mtd_info *mtd, struct nand_chip *chip,
 
 	if (chip->verify_buf(mtd, buf, mtd->writesize))
 		return -EIO;
+	
+	chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1);
 #endif
 	return 0;
 }
-- 
1.7.5.4

Re: [RFC] mtd: nand: Add a STATUS CMD after write verification

[Bastian Hecht]

2012/4/18 Bastian Hecht <hechtb@googlemail.com>:
> When using CONFIG_MTD_NAND_VERIFY_WRITE=y an extra read command is sent
> to the NAND chip after writing a page. We need an extra status command
> to avoid hick-ups that lead to page write failures.
> ---
>
> Hello all,
>
> I'm experiencing problems with my current setup and
> CONFIG_MTD_NAND_VERIFY_WRITE=y. Usually the command sequence is like
> 0x70            Status read
> 0x80 0x10       Page prog
> 0x70
> 0x80 0x10       Page prog
> 0x70
> ...
>
> When activating write verification there is a read command before the
> page prog.

I've written this unclearly. I mean if we issue multiple page writes,
the page writes are not preceeded by a status read, but by a page read
command from the last verification.

> 0x80 0x10
> 0x70
> 0x0             read
> 0x80 0x10
> 0x70
> ...
> This makes my chip write garbage, while the patch fixes it.
> Now I wonder if this problem is caused by my NAND chip only, or if this
> is a general problem that should be adressed.
> ---
>  drivers/mtd/nand/nand_base.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index 8a393f9..62d6691 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -2101,6 +2101,8 @@ static int nand_write_page(struct mtd_info *mtd, struct nand_chip *chip,
>
>        if (chip->verify_buf(mtd, buf, mtd->writesize))
>                return -EIO;
> +
> +       chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1);
>  #endif
>        return 0;
>  }
> --
> 1.7.5.4
>

Re: [RFC] mtd: nand: Add a STATUS CMD after write verification

[Artem Bityutskiy]

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On Wed, 2012-04-18 at 12:25 +0200, Bastian Hecht wrote:
> 2012/4/18 Bastian Hecht <hechtb@googlemail.com>:
> > When using CONFIG_MTD_NAND_VERIFY_WRITE=y an extra read command is sent
> > to the NAND chip after writing a page. We need an extra status command
> > to avoid hick-ups that lead to page write failures.
> > ---
> >
> > Hello all,
> >
> > I'm experiencing problems with my current setup and
> > CONFIG_MTD_NAND_VERIFY_WRITE=y. Usually the command sequence is like
> > 0x70            Status read
> > 0x80 0x10       Page prog
> > 0x70
> > 0x80 0x10       Page prog
> > 0x70
> > ...
> >
> > When activating write verification there is a read command before the
> > page prog.
> 
> I've written this unclearly. I mean if we issue multiple page writes,
> the page writes are not preceeded by a status read, but by a page read
> command from the last verification.

Looks good to me. Could you send the final patch with final commit
message. Probably a small comment in the code is also a good idea.

-- 
Best Regards,
Artem Bityutskiy

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Re: [RFC] mtd: nand: Add a STATUS CMD after write verification

[Bastian Hecht]

> Looks good to me. Could you send the final patch with final commit
> message. Probably a small comment in the code is also a good idea.

Thanks for taking a look at it. I'll post it in a sec.

> --
> Best Regards,
> Artem Bityutskiy