* [PATCH] Revert "mtd: davinci-nand: disable subpage write for keystone-nand"
@ 2017-03-27 10:26 Sekhar Nori
2017-03-29 15:03 ` Boris Brezillon
0 siblings, 1 reply; 6+ messages in thread
From: Sekhar Nori @ 2017-03-27 10:26 UTC (permalink / raw)
To: Boris Brezillon
Cc: Richard Weinberger, David Woodhouse, Brian Norris, Marek Vasut,
Cyrille Pitchen, linux-mtd, linux-kernel, Muralidharan Karicheri,
Franklin S Cooper Jr
This partly reverts commit 28c015a9daabe4ed3aeb0ccf669a3f1c2b8b81d5.
Since f6d7c1b5598b ("mtd: nand: davinci: Reinitialize the HW ECC
engine in 4bit hwctl") using subpage and 4bit HWECC works.
Revert the original workaround made for this. Tested with
mtd_subpagetest and UBIFS on K2E, K2HK, K2L EVMs.
The addition of keystone specific compatible to davinci_nand_of_match[]
contained in original commit is retained.
Cc: Muralidharan Karicheri <m-karicheri2@ti.com>
Cc: Franklin S Cooper Jr <fcooper@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
---
drivers/mtd/nand/davinci_nand.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
index 27fa8b87cd5f..56c4afed8d74 100644
--- a/drivers/mtd/nand/davinci_nand.c
+++ b/drivers/mtd/nand/davinci_nand.c
@@ -580,11 +580,6 @@ static struct davinci_nand_pdata
if (of_property_read_bool(pdev->dev.of_node,
"ti,davinci-nand-use-bbt"))
pdata->bbt_options = NAND_BBT_USE_FLASH;
-
- if (of_device_is_compatible(pdev->dev.of_node,
- "ti,keystone-nand")) {
- pdata->options |= NAND_NO_SUBPAGE_WRITE;
- }
}
return dev_get_platdata(&pdev->dev);
--
2.9.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] Revert "mtd: davinci-nand: disable subpage write for keystone-nand"
2017-03-27 10:26 [PATCH] Revert "mtd: davinci-nand: disable subpage write for keystone-nand" Sekhar Nori
@ 2017-03-29 15:03 ` Boris Brezillon
2017-03-30 7:43 ` Sekhar Nori
0 siblings, 1 reply; 6+ messages in thread
From: Boris Brezillon @ 2017-03-29 15:03 UTC (permalink / raw)
To: Sekhar Nori
Cc: Richard Weinberger, David Woodhouse, Brian Norris, Marek Vasut,
Cyrille Pitchen, linux-mtd, linux-kernel, Muralidharan Karicheri,
Franklin S Cooper Jr
On Mon, 27 Mar 2017 15:56:55 +0530
Sekhar Nori <nsekhar@ti.com> wrote:
> This partly reverts commit 28c015a9daabe4ed3aeb0ccf669a3f1c2b8b81d5.
>
> Since f6d7c1b5598b ("mtd: nand: davinci: Reinitialize the HW ECC
> engine in 4bit hwctl") using subpage and 4bit HWECC works.
>
> Revert the original workaround made for this. Tested with
> mtd_subpagetest and UBIFS on K2E, K2HK, K2L EVMs.
>
> The addition of keystone specific compatible to davinci_nand_of_match[]
> contained in original commit is retained.
Hm, it sounds like a bad idea to re-enable sub-page writes afterwards.
You might break existing systems using UBI, because UBI detects the
sub-page write feature and decides to place the VID header at a
different position depending on that.
To sum-up, you're likely to break users that have already flashed a UBI
image with the old driver.
If you want to re-enable sub-page writes, just switch back to the
"ti,davinci-nand" compatible.
>
> Cc: Muralidharan Karicheri <m-karicheri2@ti.com>
> Cc: Franklin S Cooper Jr <fcooper@ti.com>
> Signed-off-by: Sekhar Nori <nsekhar@ti.com>
> ---
> drivers/mtd/nand/davinci_nand.c | 5 -----
> 1 file changed, 5 deletions(-)
>
> diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
> index 27fa8b87cd5f..56c4afed8d74 100644
> --- a/drivers/mtd/nand/davinci_nand.c
> +++ b/drivers/mtd/nand/davinci_nand.c
> @@ -580,11 +580,6 @@ static struct davinci_nand_pdata
> if (of_property_read_bool(pdev->dev.of_node,
> "ti,davinci-nand-use-bbt"))
> pdata->bbt_options = NAND_BBT_USE_FLASH;
> -
> - if (of_device_is_compatible(pdev->dev.of_node,
> - "ti,keystone-nand")) {
> - pdata->options |= NAND_NO_SUBPAGE_WRITE;
> - }
> }
>
> return dev_get_platdata(&pdev->dev);
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] Revert "mtd: davinci-nand: disable subpage write for keystone-nand"
2017-03-29 15:03 ` Boris Brezillon
@ 2017-03-30 7:43 ` Sekhar Nori
2017-03-30 10:00 ` Boris Brezillon
0 siblings, 1 reply; 6+ messages in thread
From: Sekhar Nori @ 2017-03-30 7:43 UTC (permalink / raw)
To: Boris Brezillon
Cc: Richard Weinberger, David Woodhouse, Brian Norris, Marek Vasut,
Cyrille Pitchen, linux-mtd, linux-kernel, Muralidharan Karicheri,
Franklin S Cooper Jr
Hi Boris,
On Wednesday 29 March 2017 08:33 PM, Boris Brezillon wrote:
> On Mon, 27 Mar 2017 15:56:55 +0530
> Sekhar Nori <nsekhar@ti.com> wrote:
>
>> This partly reverts commit 28c015a9daabe4ed3aeb0ccf669a3f1c2b8b81d5.
>>
>> Since f6d7c1b5598b ("mtd: nand: davinci: Reinitialize the HW ECC
>> engine in 4bit hwctl") using subpage and 4bit HWECC works.
>>
>> Revert the original workaround made for this. Tested with
>> mtd_subpagetest and UBIFS on K2E, K2HK, K2L EVMs.
>>
>> The addition of keystone specific compatible to davinci_nand_of_match[]
>> contained in original commit is retained.
>
> Hm, it sounds like a bad idea to re-enable sub-page writes afterwards.
> You might break existing systems using UBI, because UBI detects the
> sub-page write feature and decides to place the VID header at a
> different position depending on that.
> To sum-up, you're likely to break users that have already flashed a UBI
> image with the old driver.
Okay, I didn't realize that.
> If you want to re-enable sub-page writes, just switch back to the
> "ti,davinci-nand" compatible.
How about a comment on top of the disable subpage write code explaining
that its not really needed anymore ? Something like this patch:
---8<---
From: Sekhar Nori <nsekhar@ti.com>
Date: Thu, 30 Mar 2017 13:08:30 +0530
Subject: [PATCH] mtd: nand: davinci: add comment on NAND subpage write status
on keystone
Add a comment clarifying that NAND subpage write on keystone works,
but is not being enabled in the interest of backward compatibility.
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
---
drivers/mtd/nand/davinci_nand.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
index 27fa8b87cd5f..5bf8be1cfc8c 100644
--- a/drivers/mtd/nand/davinci_nand.c
+++ b/drivers/mtd/nand/davinci_nand.c
@@ -581,6 +581,17 @@ static struct davinci_nand_pdata
"ti,davinci-nand-use-bbt"))
pdata->bbt_options = NAND_BBT_USE_FLASH;
+ /*
+ * Since kernel v4.8, this driver has been fixed to enable
+ * use of 4-bit hardware ECC with subpages and verified on
+ * TI's keystone EVMs (K2L, K2HK and K2E).
+ * However, in the interest of not breaking systems using
+ * existing UBI partitions, sub-page writes are not being
+ * (re)enabled. If you want to use subpage writes on Keystone
+ * platforms (i.e. do not have any existing UBI partitions),
+ * then remove the if() block below or pass "ti,davinci-nand"
+ * as the compatible in your device-tree file.
+ */
if (of_device_is_compatible(pdev->dev.of_node,
"ti,keystone-nand")) {
pdata->options |= NAND_NO_SUBPAGE_WRITE;
--
2.9.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] Revert "mtd: davinci-nand: disable subpage write for keystone-nand"
2017-03-30 7:43 ` Sekhar Nori
@ 2017-03-30 10:00 ` Boris Brezillon
2017-03-30 10:08 ` Sekhar Nori
0 siblings, 1 reply; 6+ messages in thread
From: Boris Brezillon @ 2017-03-30 10:00 UTC (permalink / raw)
To: Sekhar Nori, Richard Weinberger
Cc: David Woodhouse, Brian Norris, Marek Vasut, Cyrille Pitchen,
linux-mtd, linux-kernel, Muralidharan Karicheri,
Franklin S Cooper Jr
On Thu, 30 Mar 2017 13:13:58 +0530
Sekhar Nori <nsekhar@ti.com> wrote:
> Hi Boris,
>
> On Wednesday 29 March 2017 08:33 PM, Boris Brezillon wrote:
> > On Mon, 27 Mar 2017 15:56:55 +0530
> > Sekhar Nori <nsekhar@ti.com> wrote:
> >
> >> This partly reverts commit 28c015a9daabe4ed3aeb0ccf669a3f1c2b8b81d5.
> >>
> >> Since f6d7c1b5598b ("mtd: nand: davinci: Reinitialize the HW ECC
> >> engine in 4bit hwctl") using subpage and 4bit HWECC works.
> >>
> >> Revert the original workaround made for this. Tested with
> >> mtd_subpagetest and UBIFS on K2E, K2HK, K2L EVMs.
> >>
> >> The addition of keystone specific compatible to davinci_nand_of_match[]
> >> contained in original commit is retained.
> >
> > Hm, it sounds like a bad idea to re-enable sub-page writes afterwards.
> > You might break existing systems using UBI, because UBI detects the
> > sub-page write feature and decides to place the VID header at a
> > different position depending on that.
> > To sum-up, you're likely to break users that have already flashed a UBI
> > image with the old driver.
>
> Okay, I didn't realize that.
>
> > If you want to re-enable sub-page writes, just switch back to the
> > "ti,davinci-nand" compatible.
>
> How about a comment on top of the disable subpage write code explaining
> that its not really needed anymore ? Something like this patch:
>
> ---8<---
> From: Sekhar Nori <nsekhar@ti.com>
> Date: Thu, 30 Mar 2017 13:08:30 +0530
> Subject: [PATCH] mtd: nand: davinci: add comment on NAND subpage write status
> on keystone
>
> Add a comment clarifying that NAND subpage write on keystone works,
> but is not being enabled in the interest of backward compatibility.
>
> Signed-off-by: Sekhar Nori <nsekhar@ti.com>
> ---
> drivers/mtd/nand/davinci_nand.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
> index 27fa8b87cd5f..5bf8be1cfc8c 100644
> --- a/drivers/mtd/nand/davinci_nand.c
> +++ b/drivers/mtd/nand/davinci_nand.c
> @@ -581,6 +581,17 @@ static struct davinci_nand_pdata
> "ti,davinci-nand-use-bbt"))
> pdata->bbt_options = NAND_BBT_USE_FLASH;
>
> + /*
> + * Since kernel v4.8, this driver has been fixed to enable
> + * use of 4-bit hardware ECC with subpages and verified on
> + * TI's keystone EVMs (K2L, K2HK and K2E).
> + * However, in the interest of not breaking systems using
> + * existing UBI partitions, sub-page writes are not being
> + * (re)enabled. If you want to use subpage writes on Keystone
> + * platforms (i.e. do not have any existing UBI partitions),
> + * then remove the if() block below or pass "ti,davinci-nand"
> + * as the compatible in your device-tree file.
Hm, I'm not sure we should suggest to remove these lines from the code.
Just suggest to use "ti,davinci-nand" compatible.
If you're okay with that, no need to resend, I can rework the comment
accordingly before applying the patch.
Another long term solution: if UBI is the only MTD user to be
incompatible when sub-page write is activated/deactivated, maybe we can
relax the checks in UBI to allow it to attach a partition where VID
header offset is at mtd->writesize instead of
mtd->writesize >> mtd->subpage_sft.
I'll let Richard comment on that solution though.
> + */
> if (of_device_is_compatible(pdev->dev.of_node,
> "ti,keystone-nand")) {
> pdata->options |= NAND_NO_SUBPAGE_WRITE;
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] Revert "mtd: davinci-nand: disable subpage write for keystone-nand"
2017-03-30 10:00 ` Boris Brezillon
@ 2017-03-30 10:08 ` Sekhar Nori
2017-03-30 11:46 ` Boris Brezillon
0 siblings, 1 reply; 6+ messages in thread
From: Sekhar Nori @ 2017-03-30 10:08 UTC (permalink / raw)
To: Boris Brezillon, Richard Weinberger
Cc: David Woodhouse, Brian Norris, Marek Vasut, Cyrille Pitchen,
linux-mtd, linux-kernel, Muralidharan Karicheri,
Franklin S Cooper Jr
On Thursday 30 March 2017 03:30 PM, Boris Brezillon wrote:
> On Thu, 30 Mar 2017 13:13:58 +0530
> Sekhar Nori <nsekhar@ti.com> wrote:
>
>> Hi Boris,
>>
>> On Wednesday 29 March 2017 08:33 PM, Boris Brezillon wrote:
>>> On Mon, 27 Mar 2017 15:56:55 +0530
>>> Sekhar Nori <nsekhar@ti.com> wrote:
>>>
>>>> This partly reverts commit 28c015a9daabe4ed3aeb0ccf669a3f1c2b8b81d5.
>>>>
>>>> Since f6d7c1b5598b ("mtd: nand: davinci: Reinitialize the HW ECC
>>>> engine in 4bit hwctl") using subpage and 4bit HWECC works.
>>>>
>>>> Revert the original workaround made for this. Tested with
>>>> mtd_subpagetest and UBIFS on K2E, K2HK, K2L EVMs.
>>>>
>>>> The addition of keystone specific compatible to davinci_nand_of_match[]
>>>> contained in original commit is retained.
>>>
>>> Hm, it sounds like a bad idea to re-enable sub-page writes afterwards.
>>> You might break existing systems using UBI, because UBI detects the
>>> sub-page write feature and decides to place the VID header at a
>>> different position depending on that.
>>> To sum-up, you're likely to break users that have already flashed a UBI
>>> image with the old driver.
>>
>> Okay, I didn't realize that.
>>
>>> If you want to re-enable sub-page writes, just switch back to the
>>> "ti,davinci-nand" compatible.
>>
>> How about a comment on top of the disable subpage write code explaining
>> that its not really needed anymore ? Something like this patch:
>>
>> ---8<---
>> From: Sekhar Nori <nsekhar@ti.com>
>> Date: Thu, 30 Mar 2017 13:08:30 +0530
>> Subject: [PATCH] mtd: nand: davinci: add comment on NAND subpage write status
>> on keystone
>>
>> Add a comment clarifying that NAND subpage write on keystone works,
>> but is not being enabled in the interest of backward compatibility.
>>
>> Signed-off-by: Sekhar Nori <nsekhar@ti.com>
>> ---
>> drivers/mtd/nand/davinci_nand.c | 11 +++++++++++
>> 1 file changed, 11 insertions(+)
>>
>> diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
>> index 27fa8b87cd5f..5bf8be1cfc8c 100644
>> --- a/drivers/mtd/nand/davinci_nand.c
>> +++ b/drivers/mtd/nand/davinci_nand.c
>> @@ -581,6 +581,17 @@ static struct davinci_nand_pdata
>> "ti,davinci-nand-use-bbt"))
>> pdata->bbt_options = NAND_BBT_USE_FLASH;
>>
>> + /*
>> + * Since kernel v4.8, this driver has been fixed to enable
>> + * use of 4-bit hardware ECC with subpages and verified on
>> + * TI's keystone EVMs (K2L, K2HK and K2E).
>> + * However, in the interest of not breaking systems using
>> + * existing UBI partitions, sub-page writes are not being
>> + * (re)enabled. If you want to use subpage writes on Keystone
>> + * platforms (i.e. do not have any existing UBI partitions),
>> + * then remove the if() block below or pass "ti,davinci-nand"
>> + * as the compatible in your device-tree file.
>
> Hm, I'm not sure we should suggest to remove these lines from the code.
> Just suggest to use "ti,davinci-nand" compatible.
Thats fine with me. Today, this if() block is the only place where
ti,keystone-nand is used. If in future it gets used for something else
(yet unknown), then the comment might start to get misleading. Thats why
just removing the code seemed like a safer option to me.
But the main intention was to document that subpage is not really broken
on K2 platform. So, what you suggest will do as well.
Thanks,
Sekhar
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] Revert "mtd: davinci-nand: disable subpage write for keystone-nand"
2017-03-30 10:08 ` Sekhar Nori
@ 2017-03-30 11:46 ` Boris Brezillon
0 siblings, 0 replies; 6+ messages in thread
From: Boris Brezillon @ 2017-03-30 11:46 UTC (permalink / raw)
To: Sekhar Nori
Cc: Richard Weinberger, David Woodhouse, Brian Norris, Marek Vasut,
Cyrille Pitchen, linux-mtd, linux-kernel, Muralidharan Karicheri,
Franklin S Cooper Jr
On Thu, 30 Mar 2017 15:38:54 +0530
Sekhar Nori <nsekhar@ti.com> wrote:
> On Thursday 30 March 2017 03:30 PM, Boris Brezillon wrote:
> > On Thu, 30 Mar 2017 13:13:58 +0530
> > Sekhar Nori <nsekhar@ti.com> wrote:
> >
> >> Hi Boris,
> >>
> >> On Wednesday 29 March 2017 08:33 PM, Boris Brezillon wrote:
> >>> On Mon, 27 Mar 2017 15:56:55 +0530
> >>> Sekhar Nori <nsekhar@ti.com> wrote:
> >>>
> >>>> This partly reverts commit 28c015a9daabe4ed3aeb0ccf669a3f1c2b8b81d5.
> >>>>
> >>>> Since f6d7c1b5598b ("mtd: nand: davinci: Reinitialize the HW ECC
> >>>> engine in 4bit hwctl") using subpage and 4bit HWECC works.
> >>>>
> >>>> Revert the original workaround made for this. Tested with
> >>>> mtd_subpagetest and UBIFS on K2E, K2HK, K2L EVMs.
> >>>>
> >>>> The addition of keystone specific compatible to davinci_nand_of_match[]
> >>>> contained in original commit is retained.
> >>>
> >>> Hm, it sounds like a bad idea to re-enable sub-page writes afterwards.
> >>> You might break existing systems using UBI, because UBI detects the
> >>> sub-page write feature and decides to place the VID header at a
> >>> different position depending on that.
> >>> To sum-up, you're likely to break users that have already flashed a UBI
> >>> image with the old driver.
> >>
> >> Okay, I didn't realize that.
> >>
> >>> If you want to re-enable sub-page writes, just switch back to the
> >>> "ti,davinci-nand" compatible.
> >>
> >> How about a comment on top of the disable subpage write code explaining
> >> that its not really needed anymore ? Something like this patch:
> >>
> >> ---8<---
> >> From: Sekhar Nori <nsekhar@ti.com>
> >> Date: Thu, 30 Mar 2017 13:08:30 +0530
> >> Subject: [PATCH] mtd: nand: davinci: add comment on NAND subpage write status
> >> on keystone
> >>
> >> Add a comment clarifying that NAND subpage write on keystone works,
> >> but is not being enabled in the interest of backward compatibility.
> >>
> >> Signed-off-by: Sekhar Nori <nsekhar@ti.com>
> >> ---
> >> drivers/mtd/nand/davinci_nand.c | 11 +++++++++++
> >> 1 file changed, 11 insertions(+)
> >>
> >> diff --git a/drivers/mtd/nand/davinci_nand.c b/drivers/mtd/nand/davinci_nand.c
> >> index 27fa8b87cd5f..5bf8be1cfc8c 100644
> >> --- a/drivers/mtd/nand/davinci_nand.c
> >> +++ b/drivers/mtd/nand/davinci_nand.c
> >> @@ -581,6 +581,17 @@ static struct davinci_nand_pdata
> >> "ti,davinci-nand-use-bbt"))
> >> pdata->bbt_options = NAND_BBT_USE_FLASH;
> >>
> >> + /*
> >> + * Since kernel v4.8, this driver has been fixed to enable
> >> + * use of 4-bit hardware ECC with subpages and verified on
> >> + * TI's keystone EVMs (K2L, K2HK and K2E).
> >> + * However, in the interest of not breaking systems using
> >> + * existing UBI partitions, sub-page writes are not being
> >> + * (re)enabled. If you want to use subpage writes on Keystone
> >> + * platforms (i.e. do not have any existing UBI partitions),
> >> + * then remove the if() block below or pass "ti,davinci-nand"
> >> + * as the compatible in your device-tree file.
> >
> > Hm, I'm not sure we should suggest to remove these lines from the code.
> > Just suggest to use "ti,davinci-nand" compatible.
Can you send a separate patch so that it appears on its own in
patchwork?
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2017-03-30 11:46 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-03-27 10:26 [PATCH] Revert "mtd: davinci-nand: disable subpage write for keystone-nand" Sekhar Nori
2017-03-29 15:03 ` Boris Brezillon
2017-03-30 7:43 ` Sekhar Nori
2017-03-30 10:00 ` Boris Brezillon
2017-03-30 10:08 ` Sekhar Nori
2017-03-30 11:46 ` Boris Brezillon
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