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| Started by | Karl Beldan <kbeldan@baylibre.com> |
|---|---|
| First post | 2016-08-29 09:50 +0200 |
| Last post | 2016-08-29 22:50 +0200 |
| Articles | 4 — 3 participants |
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[PATCH] mtd: nand: davinci: Reinitialize the HW ECC engine in 4bit hwctl Karl Beldan <kbeldan@baylibre.com> - 2016-08-29 09:50 +0200
Re: [PATCH] mtd: nand: davinci: Reinitialize the HW ECC engine in 4bit hwctl Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-08-29 12:00 +0200
Re: [PATCH] mtd: nand: davinci: Reinitialize the HW ECC engine in 4bit hwctl Boris Brezillon <boris.brezillon@free-electrons.com> - 2016-08-29 22:50 +0200
Re: [PATCH] mtd: nand: davinci: Reinitialize the HW ECC engine in 4bit hwctl Brian Norris <computersforpeace@gmail.com> - 2016-08-29 22:50 +0200
| From | Karl Beldan <kbeldan@baylibre.com> |
|---|---|
| Date | 2016-08-29 09:50 +0200 |
| Subject | [PATCH] mtd: nand: davinci: Reinitialize the HW ECC engine in 4bit hwctl |
| Message-ID | <sbpup-4sn-7@gated-at.bofh.it> |
This fixes subpage writes when using 4-bit HW ECC.
There has been numerous reports about ECC errors with devices using this
driver for a while. Also the 4-bit ECC has been reported as broken with
subpages in [1] and with 16 bits NANDs in the driver and in mach* board
files both in mainline and in the vendor BSPs.
What I saw with 4-bit ECC on a 16bits NAND (on an LCDK) which got me to
try reinitializing the ECC engine:
- R/W on whole pages properly generates/checks RS code
- try writing the 1st subpage only of a blank page, the subpage is well
written and the RS code properly generated, re-reading the same page
the HW detects some ECC error, reading the same page again no ECC
error is detected
Note that the ECC engine is already reinitialized in the 1-bit case.
Tested on my LCDK with UBI+UBIFS using subpages.
This could potentially get rid of the issue workarounded in [1].
[1] 28c015a9daab ("mtd: davinci-nand: disable subpage write for keystone-nand")
Signed-off-by: Karl Beldan <kbeldan@baylibre.com>
---
drivers/mtd/nand/davinci_nand.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
index cc07ba0..27fa8b8 100644
--- a/drivers/mtd/nand/davinci_nand.c
+++ b/drivers/mtd/nand/davinci_nand.c
@@ -240,6 +240,9 @@ static void nand_davinci_hwctl_4bit(struct mtd_info *mtd, int mode)
unsigned long flags;
u32 val;
+ /* Reset ECC hardware */
+ davinci_nand_readl(info, NAND_4BIT_ECC1_OFFSET);
+
spin_lock_irqsave(&davinci_nand_lock, flags);
/* Start 4-bit ECC calculation for read/write */
--
2.9.2
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| From | Boris Brezillon <boris.brezillon@free-electrons.com> |
|---|---|
| Date | 2016-08-29 12:00 +0200 |
| Subject | Re: [PATCH] mtd: nand: davinci: Reinitialize the HW ECC engine in 4bit hwctl |
| Message-ID | <sbrwe-5Fk-27@gated-at.bofh.it> |
| In reply to | #1471602 |
On Mon, 29 Aug 2016 07:45:49 +0000
Karl Beldan <kbeldan@baylibre.com> wrote:
> This fixes subpage writes when using 4-bit HW ECC.
>
> There has been numerous reports about ECC errors with devices using this
> driver for a while. Also the 4-bit ECC has been reported as broken with
> subpages in [1] and with 16 bits NANDs in the driver and in mach* board
> files both in mainline and in the vendor BSPs.
>
> What I saw with 4-bit ECC on a 16bits NAND (on an LCDK) which got me to
> try reinitializing the ECC engine:
> - R/W on whole pages properly generates/checks RS code
> - try writing the 1st subpage only of a blank page, the subpage is well
> written and the RS code properly generated, re-reading the same page
> the HW detects some ECC error, reading the same page again no ECC
> error is detected
>
> Note that the ECC engine is already reinitialized in the 1-bit case.
>
> Tested on my LCDK with UBI+UBIFS using subpages.
> This could potentially get rid of the issue workarounded in [1].
>
> [1] 28c015a9daab ("mtd: davinci-nand: disable subpage write for keystone-nand")
>
> Signed-off-by: Karl Beldan <kbeldan@baylibre.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Brian, can you take this patch directly in your tree. If that's not
possible, let me know, I'll add the Fixes and Cc:stable tags and take
it for 4.9.
Thanks,
Boris
> ---
> drivers/mtd/nand/davinci_nand.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
> index cc07ba0..27fa8b8 100644
> --- a/drivers/mtd/nand/davinci_nand.c
> +++ b/drivers/mtd/nand/davinci_nand.c
> @@ -240,6 +240,9 @@ static void nand_davinci_hwctl_4bit(struct mtd_info *mtd, int mode)
> unsigned long flags;
> u32 val;
>
> + /* Reset ECC hardware */
> + davinci_nand_readl(info, NAND_4BIT_ECC1_OFFSET);
> +
> spin_lock_irqsave(&davinci_nand_lock, flags);
>
> /* Start 4-bit ECC calculation for read/write */
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| From | Boris Brezillon <boris.brezillon@free-electrons.com> |
|---|---|
| Date | 2016-08-29 22:50 +0200 |
| Subject | Re: [PATCH] mtd: nand: davinci: Reinitialize the HW ECC engine in 4bit hwctl |
| Message-ID | <sbBFf-3H1-13@gated-at.bofh.it> |
| In reply to | #1471690 |
On Mon, 29 Aug 2016 13:38:47 -0700
Brian Norris <computersforpeace@gmail.com> wrote:
> On Mon, Aug 29, 2016 at 11:59:30AM +0200, Boris Brezillon wrote:
> > On Mon, 29 Aug 2016 07:45:49 +0000
> > Karl Beldan <kbeldan@baylibre.com> wrote:
> >
> > > This fixes subpage writes when using 4-bit HW ECC.
> > >
> > > There has been numerous reports about ECC errors with devices using this
> > > driver for a while. Also the 4-bit ECC has been reported as broken with
> > > subpages in [1] and with 16 bits NANDs in the driver and in mach* board
> > > files both in mainline and in the vendor BSPs.
> > >
> > > What I saw with 4-bit ECC on a 16bits NAND (on an LCDK) which got me to
> > > try reinitializing the ECC engine:
> > > - R/W on whole pages properly generates/checks RS code
> > > - try writing the 1st subpage only of a blank page, the subpage is well
> > > written and the RS code properly generated, re-reading the same page
> > > the HW detects some ECC error, reading the same page again no ECC
> > > error is detected
> > >
> > > Note that the ECC engine is already reinitialized in the 1-bit case.
> > >
> > > Tested on my LCDK with UBI+UBIFS using subpages.
> > > This could potentially get rid of the issue workarounded in [1].
> > >
> > > [1] 28c015a9daab ("mtd: davinci-nand: disable subpage write for keystone-nand")
> > >
> > > Signed-off-by: Karl Beldan <kbeldan@baylibre.com>
> >
> > Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> >
> > Brian, can you take this patch directly in your tree. If that's not
> > possible, let me know, I'll add the Fixes and Cc:stable tags and take
> > it for 4.9.
>
> Would this be correct?
>
> Fixes: 6a4123e581b3 ("mtd: nand: davinci_nand, 4-bit ECC for smallpage")
I'd say so. At least this is where nand_davinci_hwctl_4bit() was
introduced, and it did not contain this 'reset' step.
>
> Brian
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| From | Brian Norris <computersforpeace@gmail.com> |
|---|---|
| Date | 2016-08-29 22:50 +0200 |
| Subject | Re: [PATCH] mtd: nand: davinci: Reinitialize the HW ECC engine in 4bit hwctl |
| Message-ID | <sbBFg-3H1-15@gated-at.bofh.it> |
| In reply to | #1471690 |
On Mon, Aug 29, 2016 at 11:59:30AM +0200, Boris Brezillon wrote:
> On Mon, 29 Aug 2016 07:45:49 +0000
> Karl Beldan <kbeldan@baylibre.com> wrote:
>
> > This fixes subpage writes when using 4-bit HW ECC.
> >
> > There has been numerous reports about ECC errors with devices using this
> > driver for a while. Also the 4-bit ECC has been reported as broken with
> > subpages in [1] and with 16 bits NANDs in the driver and in mach* board
> > files both in mainline and in the vendor BSPs.
> >
> > What I saw with 4-bit ECC on a 16bits NAND (on an LCDK) which got me to
> > try reinitializing the ECC engine:
> > - R/W on whole pages properly generates/checks RS code
> > - try writing the 1st subpage only of a blank page, the subpage is well
> > written and the RS code properly generated, re-reading the same page
> > the HW detects some ECC error, reading the same page again no ECC
> > error is detected
> >
> > Note that the ECC engine is already reinitialized in the 1-bit case.
> >
> > Tested on my LCDK with UBI+UBIFS using subpages.
> > This could potentially get rid of the issue workarounded in [1].
> >
> > [1] 28c015a9daab ("mtd: davinci-nand: disable subpage write for keystone-nand")
> >
> > Signed-off-by: Karl Beldan <kbeldan@baylibre.com>
>
> Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
>
> Brian, can you take this patch directly in your tree. If that's not
> possible, let me know, I'll add the Fixes and Cc:stable tags and take
> it for 4.9.
Would this be correct?
Fixes: 6a4123e581b3 ("mtd: nand: davinci_nand, 4-bit ECC for smallpage")
Brian
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