[LINUX,v17,1/2] mtd: rawnand: nand_micron: Do not over write driver's read_page()/write_page()
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Message ID 20190625044630.31717-1-naga.sureshkumar.relli@xilinx.com
State Changes Requested
Delegated to: Miquel Raynal
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Series
  • [LINUX,v17,1/2] mtd: rawnand: nand_micron: Do not over write driver's read_page()/write_page()
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Commit Message

Naga Sureshkumar Relli June 25, 2019, 4:46 a.m. UTC
Add check before assigning chip->ecc.read_page() and chip->ecc.write_page()

Signed-off-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
---
 drivers/mtd/nand/raw/nand_micron.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

Comments

Helmut Grohne June 25, 2019, 2:11 p.m. UTC | #1
On Tue, Jun 25, 2019 at 06:46:29AM +0200, Naga Sureshkumar Relli wrote:
> --- a/drivers/mtd/nand/raw/nand_micron.c
> +++ b/drivers/mtd/nand/raw/nand_micron.c
> @@ -500,8 +500,11 @@ static int micron_nand_init(struct nand_chip *chip)
>  		chip->ecc.size = 512;
>  		chip->ecc.strength = chip->base.eccreq.strength;
>  		chip->ecc.algo = NAND_ECC_BCH;
> -		chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> -		chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
> +		if (!chip->ecc.read_page)
> +			chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> +
> +		if (!chip->ecc.write_page)
> +			chip->ecc.write_page = micron_nand_write_page_on_die_ecc;

When used with pl353_nand.c, this change prioritizes the
pl353_nand_read_page_raw/pl353_nand_write_page_raw implementations over
micron_nand_read_page_on_die_ecc/micron_nand_write_page_on_die_ecc. The
pl353 implementations don't check the status register of the flash for
NAND_ECC_STATUS_WRITE_RECOMMENDED nor do they update ecc_stats.failed in
any way. Unless I am mistaken, this implies that bitflips cannot be
detected at all anymore.

However, this is the change that makes a MT29F2G08ABAEAWP practically
work with jffs2 on the Zynq platform.

In this context, I countered a document from Micron[1] indicating that
their on-die chips are incompatible with jffs2 as is, because the on-die
oob layout is incompatible with jffs2. I suppose that using the raw
variants puts jffs2 in full control of the oob area, but is this really
the correct solution?

Helmut

[1] https://www.micron.com/~/media/Documents/Products/Technical%20Note/NAND%20Flash/tn2975_enable_on-die-ECC_NAND_JFFS2.pdf
Boris Brezillon June 26, 2019, 6:48 a.m. UTC | #2
On Mon, 24 Jun 2019 22:46:29 -0600
Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com> wrote:

> Add check before assigning chip->ecc.read_page() and chip->ecc.write_page()
> 
> Signed-off-by: Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com>
> ---
>  drivers/mtd/nand/raw/nand_micron.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/nand_micron.c b/drivers/mtd/nand/raw/nand_micron.c
> index cbd4f09ac178..565f2696c747 100644
> --- a/drivers/mtd/nand/raw/nand_micron.c
> +++ b/drivers/mtd/nand/raw/nand_micron.c
> @@ -500,8 +500,11 @@ static int micron_nand_init(struct nand_chip *chip)
>  		chip->ecc.size = 512;
>  		chip->ecc.strength = chip->base.eccreq.strength;
>  		chip->ecc.algo = NAND_ECC_BCH;
> -		chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> -		chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
> +		if (!chip->ecc.read_page)
> +			chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> +
> +		if (!chip->ecc.write_page)
> +			chip->ecc.write_page = micron_nand_write_page_on_die_ecc;

That's wrong, if you don't want on-die ECC to be used, simply don't set
nand-ecc-mode to "on-die".

>  
>  		if (ondie == MICRON_ON_DIE_MANDATORY) {
>  			chip->ecc.read_page_raw = nand_read_page_raw_notsupp;
Naga Sureshkumar Relli June 26, 2019, 11:22 a.m. UTC | #3
Hi Boris,

> -----Original Message-----
> From: Boris Brezillon <boris.brezillon@collabora.com>
> Sent: Wednesday, June 26, 2019 12:18 PM
> To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de; richard@nod.at;
> dwmw2@infradead.org; computersforpeace@gmail.com; marek.vasut@gmail.com;
> vigneshr@ti.com; bbrezillon@kernel.org; yamada.masahiro@socionext.com; linux-
> mtd@lists.infradead.org; linux-kernel@vger.kernel.org
> Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not over write
> driver's read_page()/write_page()
> 
> On Mon, 24 Jun 2019 22:46:29 -0600
> Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com> wrote:
> 
> > Add check before assigning chip->ecc.read_page() and
> > chip->ecc.write_page()
> >
> > Signed-off-by: Naga Sureshkumar Relli
> > <naga.sureshkumar.relli@xilinx.com>
> > ---
> >  drivers/mtd/nand/raw/nand_micron.c | 7 +++++--
> >  1 file changed, 5 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/mtd/nand/raw/nand_micron.c
> > b/drivers/mtd/nand/raw/nand_micron.c
> > index cbd4f09ac178..565f2696c747 100644
> > --- a/drivers/mtd/nand/raw/nand_micron.c
> > +++ b/drivers/mtd/nand/raw/nand_micron.c
> > @@ -500,8 +500,11 @@ static int micron_nand_init(struct nand_chip *chip)
> >  		chip->ecc.size = 512;
> >  		chip->ecc.strength = chip->base.eccreq.strength;
> >  		chip->ecc.algo = NAND_ECC_BCH;
> > -		chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > -		chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
> > +		if (!chip->ecc.read_page)
> > +			chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > +
> > +		if (!chip->ecc.write_page)
> > +			chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
> 
> That's wrong, if you don't want on-die ECC to be used, simply don't set nand-ecc-mode to "on-
> die".
Ok. But if we want to use on-die ECC then you mean to say it is mandatory to use micron_nand_read/write_page_on_die_ecc()?

Regards,
Naga Sureshkumar Relli
> 
> >
> >  		if (ondie == MICRON_ON_DIE_MANDATORY) {
> >  			chip->ecc.read_page_raw = nand_read_page_raw_notsupp;
Boris Brezillon June 26, 2019, 11:27 a.m. UTC | #4
On Wed, 26 Jun 2019 11:22:33 +0000
Naga Sureshkumar Relli <nagasure@xilinx.com> wrote:

> Hi Boris,
> 
> > -----Original Message-----
> > From: Boris Brezillon <boris.brezillon@collabora.com>
> > Sent: Wednesday, June 26, 2019 12:18 PM
> > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de; richard@nod.at;
> > dwmw2@infradead.org; computersforpeace@gmail.com; marek.vasut@gmail.com;
> > vigneshr@ti.com; bbrezillon@kernel.org; yamada.masahiro@socionext.com; linux-
> > mtd@lists.infradead.org; linux-kernel@vger.kernel.org
> > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not over write
> > driver's read_page()/write_page()
> > 
> > On Mon, 24 Jun 2019 22:46:29 -0600
> > Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com> wrote:
> >   
> > > Add check before assigning chip->ecc.read_page() and
> > > chip->ecc.write_page()
> > >
> > > Signed-off-by: Naga Sureshkumar Relli
> > > <naga.sureshkumar.relli@xilinx.com>
> > > ---
> > >  drivers/mtd/nand/raw/nand_micron.c | 7 +++++--
> > >  1 file changed, 5 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/mtd/nand/raw/nand_micron.c
> > > b/drivers/mtd/nand/raw/nand_micron.c
> > > index cbd4f09ac178..565f2696c747 100644
> > > --- a/drivers/mtd/nand/raw/nand_micron.c
> > > +++ b/drivers/mtd/nand/raw/nand_micron.c
> > > @@ -500,8 +500,11 @@ static int micron_nand_init(struct nand_chip *chip)
> > >  		chip->ecc.size = 512;
> > >  		chip->ecc.strength = chip->base.eccreq.strength;
> > >  		chip->ecc.algo = NAND_ECC_BCH;
> > > -		chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > > -		chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
> > > +		if (!chip->ecc.read_page)
> > > +			chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > > +
> > > +		if (!chip->ecc.write_page)
> > > +			chip->ecc.write_page = micron_nand_write_page_on_die_ecc;  
> > 
> > That's wrong, if you don't want on-die ECC to be used, simply don't set nand-ecc-mode to "on-
> > die".  
> Ok. But if we want to use on-die ECC then you mean to say it is mandatory to use micron_nand_read/write_page_on_die_ecc()?

Absolutely, and if it doesn't work that means you driver does not
implement raw accesses correctly, which means it's still buggy...
Naga Sureshkumar Relli June 26, 2019, 11:51 a.m. UTC | #5
Hi Boris,

> -----Original Message-----
> From: Boris Brezillon <boris.brezillon@collabora.com>
> Sent: Wednesday, June 26, 2019 4:57 PM
> To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de; richard@nod.at;
> dwmw2@infradead.org; computersforpeace@gmail.com; marek.vasut@gmail.com;
> vigneshr@ti.com; bbrezillon@kernel.org; yamada.masahiro@socionext.com; linux-
> mtd@lists.infradead.org; linux-kernel@vger.kernel.org
> Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not over write
> driver's read_page()/write_page()
> 
> On Wed, 26 Jun 2019 11:22:33 +0000
> Naga Sureshkumar Relli <nagasure@xilinx.com> wrote:
> 
> > Hi Boris,
> >
> > > -----Original Message-----
> > > From: Boris Brezillon <boris.brezillon@collabora.com>
> > > Sent: Wednesday, June 26, 2019 12:18 PM
> > > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de;
> > > richard@nod.at; dwmw2@infradead.org; computersforpeace@gmail.com;
> > > marek.vasut@gmail.com; vigneshr@ti.com; bbrezillon@kernel.org;
> > > yamada.masahiro@socionext.com; linux- mtd@lists.infradead.org;
> > > linux-kernel@vger.kernel.org
> > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not
> > > over write driver's read_page()/write_page()
> > >
> > > On Mon, 24 Jun 2019 22:46:29 -0600
> > > Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com> wrote:
> > >
> > > > Add check before assigning chip->ecc.read_page() and
> > > > chip->ecc.write_page()
> > > >
> > > > Signed-off-by: Naga Sureshkumar Relli
> > > > <naga.sureshkumar.relli@xilinx.com>
> > > > ---
> > > >  drivers/mtd/nand/raw/nand_micron.c | 7 +++++--
> > > >  1 file changed, 5 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/mtd/nand/raw/nand_micron.c
> > > > b/drivers/mtd/nand/raw/nand_micron.c
> > > > index cbd4f09ac178..565f2696c747 100644
> > > > --- a/drivers/mtd/nand/raw/nand_micron.c
> > > > +++ b/drivers/mtd/nand/raw/nand_micron.c
> > > > @@ -500,8 +500,11 @@ static int micron_nand_init(struct nand_chip *chip)
> > > >  		chip->ecc.size = 512;
> > > >  		chip->ecc.strength = chip->base.eccreq.strength;
> > > >  		chip->ecc.algo = NAND_ECC_BCH;
> > > > -		chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > > > -		chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
> > > > +		if (!chip->ecc.read_page)
> > > > +			chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > > > +
> > > > +		if (!chip->ecc.write_page)
> > > > +			chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
> > >
> > > That's wrong, if you don't want on-die ECC to be used, simply don't
> > > set nand-ecc-mode to "on- die".
> > Ok. But if we want to use on-die ECC then you mean to say it is mandatory to use
> micron_nand_read/write_page_on_die_ecc()?
> 
> Absolutely, and if it doesn't work that means you driver does not
> implement raw accesses correctly, which means it's still buggy...
I agree. But let's say, if there is a limitation with the controller. Then it is must to have this check right?
I mean, for pl353 controller, we must clear the CS during the data phase, hence we are splitting the 
Transfer in the pl353_read/write_page_raw().
+	pl353_nand_read_data_op(chip, buf, mtd->writesize, false);
+	p = chip->oob_poi;
+	pl353_nand_read_data_op(chip, p,
+				(mtd->oobsize -
+				PL353_NAND_LAST_TRANSFER_LENGTH), false);
+	p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
+	xnfc->dataphase_addrflags |= PL353_NAND_CLEAR_CS;
+	pl353_nand_read_data_op(chip, p, PL353_NAND_LAST_TRANSFER_LENGTH,
+				false);
As the above sequence is needed even for raw access, PL353 is unable to use the on_die_page reads.

Thanks,
Naga Sureshkumar Relli
Boris Brezillon June 26, 2019, 12:04 p.m. UTC | #6
On Wed, 26 Jun 2019 11:51:12 +0000
Naga Sureshkumar Relli <nagasure@xilinx.com> wrote:

> Hi Boris,
> 
> > -----Original Message-----
> > From: Boris Brezillon <boris.brezillon@collabora.com>
> > Sent: Wednesday, June 26, 2019 4:57 PM
> > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de; richard@nod.at;
> > dwmw2@infradead.org; computersforpeace@gmail.com; marek.vasut@gmail.com;
> > vigneshr@ti.com; bbrezillon@kernel.org; yamada.masahiro@socionext.com; linux-
> > mtd@lists.infradead.org; linux-kernel@vger.kernel.org
> > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not over write
> > driver's read_page()/write_page()
> > 
> > On Wed, 26 Jun 2019 11:22:33 +0000
> > Naga Sureshkumar Relli <nagasure@xilinx.com> wrote:
> >   
> > > Hi Boris,
> > >  
> > > > -----Original Message-----
> > > > From: Boris Brezillon <boris.brezillon@collabora.com>
> > > > Sent: Wednesday, June 26, 2019 12:18 PM
> > > > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > > > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de;
> > > > richard@nod.at; dwmw2@infradead.org; computersforpeace@gmail.com;
> > > > marek.vasut@gmail.com; vigneshr@ti.com; bbrezillon@kernel.org;
> > > > yamada.masahiro@socionext.com; linux- mtd@lists.infradead.org;
> > > > linux-kernel@vger.kernel.org
> > > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not
> > > > over write driver's read_page()/write_page()
> > > >
> > > > On Mon, 24 Jun 2019 22:46:29 -0600
> > > > Naga Sureshkumar Relli <naga.sureshkumar.relli@xilinx.com> wrote:
> > > >  
> > > > > Add check before assigning chip->ecc.read_page() and
> > > > > chip->ecc.write_page()
> > > > >
> > > > > Signed-off-by: Naga Sureshkumar Relli
> > > > > <naga.sureshkumar.relli@xilinx.com>
> > > > > ---
> > > > >  drivers/mtd/nand/raw/nand_micron.c | 7 +++++--
> > > > >  1 file changed, 5 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/drivers/mtd/nand/raw/nand_micron.c
> > > > > b/drivers/mtd/nand/raw/nand_micron.c
> > > > > index cbd4f09ac178..565f2696c747 100644
> > > > > --- a/drivers/mtd/nand/raw/nand_micron.c
> > > > > +++ b/drivers/mtd/nand/raw/nand_micron.c
> > > > > @@ -500,8 +500,11 @@ static int micron_nand_init(struct nand_chip *chip)
> > > > >  		chip->ecc.size = 512;
> > > > >  		chip->ecc.strength = chip->base.eccreq.strength;
> > > > >  		chip->ecc.algo = NAND_ECC_BCH;
> > > > > -		chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > > > > -		chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
> > > > > +		if (!chip->ecc.read_page)
> > > > > +			chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > > > > +
> > > > > +		if (!chip->ecc.write_page)
> > > > > +			chip->ecc.write_page = micron_nand_write_page_on_die_ecc;  
> > > >
> > > > That's wrong, if you don't want on-die ECC to be used, simply don't
> > > > set nand-ecc-mode to "on- die".  
> > > Ok. But if we want to use on-die ECC then you mean to say it is mandatory to use  
> > micron_nand_read/write_page_on_die_ecc()?
> > 
> > Absolutely, and if it doesn't work that means you driver does not
> > implement raw accesses correctly, which means it's still buggy...  
> I agree. But let's say, if there is a limitation with the controller. Then it is must to have this check right?
> I mean, for pl353 controller, we must clear the CS during the data phase, hence we are splitting the 
> Transfer in the pl353_read/write_page_raw().
> +	pl353_nand_read_data_op(chip, buf, mtd->writesize, false);
> +	p = chip->oob_poi;
> +	pl353_nand_read_data_op(chip, p,
> +				(mtd->oobsize -
> +				PL353_NAND_LAST_TRANSFER_LENGTH), false);
> +	p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
> +	xnfc->dataphase_addrflags |= PL353_NAND_CLEAR_CS;
> +	pl353_nand_read_data_op(chip, p, PL353_NAND_LAST_TRANSFER_LENGTH,
> +				false);
> As the above sequence is needed even for raw access, PL353 is unable to use the on_die_page reads.

This "de-assert CS on last access" logic should be done in the
exec_op() implementation. I also wonder how that works for operations
that don't have data cycles. Oh, BTW, most chips are CE-don't-care,
which means you can assert/de-assert CS on each read_data_op() without
any issues.
Naga Sureshkumar Relli June 26, 2019, 12:12 p.m. UTC | #7
Hi Boris,

> -----Original Message-----
> From: Boris Brezillon <boris.brezillon@collabora.com>
> Sent: Wednesday, June 26, 2019 5:34 PM
> To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de; richard@nod.at;
> dwmw2@infradead.org; computersforpeace@gmail.com; marek.vasut@gmail.com;
> vigneshr@ti.com; bbrezillon@kernel.org; yamada.masahiro@socionext.com; linux-
> mtd@lists.infradead.org; linux-kernel@vger.kernel.org
> Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not over write
> driver's read_page()/write_page()
> 
> On Wed, 26 Jun 2019 11:51:12 +0000
> Naga Sureshkumar Relli <nagasure@xilinx.com> wrote:
> 
> > Hi Boris,
> >
> > > -----Original Message-----
> > > From: Boris Brezillon <boris.brezillon@collabora.com>
> > > Sent: Wednesday, June 26, 2019 4:57 PM
> > > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de;
> > > richard@nod.at; dwmw2@infradead.org; computersforpeace@gmail.com;
> > > marek.vasut@gmail.com; vigneshr@ti.com; bbrezillon@kernel.org;
> > > yamada.masahiro@socionext.com; linux- mtd@lists.infradead.org;
> > > linux-kernel@vger.kernel.org
> > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not
> > > over write driver's read_page()/write_page()
> > >
> > > On Wed, 26 Jun 2019 11:22:33 +0000
> > > Naga Sureshkumar Relli <nagasure@xilinx.com> wrote:
> > >
> > > > Hi Boris,
> > > >
> > > > > -----Original Message-----
> > > > > From: Boris Brezillon <boris.brezillon@collabora.com>
> > > > > Sent: Wednesday, June 26, 2019 12:18 PM
> > > > > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > > > > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de;
> > > > > richard@nod.at; dwmw2@infradead.org;
> > > > > computersforpeace@gmail.com; marek.vasut@gmail.com;
> > > > > vigneshr@ti.com; bbrezillon@kernel.org;
> > > > > yamada.masahiro@socionext.com; linux- mtd@lists.infradead.org;
> > > > > linux-kernel@vger.kernel.org
> > > > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do
> > > > > not over write driver's read_page()/write_page()
> > > > >
> > > > > On Mon, 24 Jun 2019 22:46:29 -0600 Naga Sureshkumar Relli
> > > > > <naga.sureshkumar.relli@xilinx.com> wrote:
> > > > >
> > > > > > Add check before assigning chip->ecc.read_page() and
> > > > > > chip->ecc.write_page()
> > > > > >
> > > > > > Signed-off-by: Naga Sureshkumar Relli
> > > > > > <naga.sureshkumar.relli@xilinx.com>
> > > > > > ---
> > > > > >  drivers/mtd/nand/raw/nand_micron.c | 7 +++++--
> > > > > >  1 file changed, 5 insertions(+), 2 deletions(-)
> > > > > >
> > > > > > diff --git a/drivers/mtd/nand/raw/nand_micron.c
> > > > > > b/drivers/mtd/nand/raw/nand_micron.c
> > > > > > index cbd4f09ac178..565f2696c747 100644
> > > > > > --- a/drivers/mtd/nand/raw/nand_micron.c
> > > > > > +++ b/drivers/mtd/nand/raw/nand_micron.c
> > > > > > @@ -500,8 +500,11 @@ static int micron_nand_init(struct nand_chip *chip)
> > > > > >  		chip->ecc.size = 512;
> > > > > >  		chip->ecc.strength = chip->base.eccreq.strength;
> > > > > >  		chip->ecc.algo = NAND_ECC_BCH;
> > > > > > -		chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > > > > > -		chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
> > > > > > +		if (!chip->ecc.read_page)
> > > > > > +			chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > > > > > +
> > > > > > +		if (!chip->ecc.write_page)
> > > > > > +			chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
> > > > >
> > > > > That's wrong, if you don't want on-die ECC to be used, simply
> > > > > don't set nand-ecc-mode to "on- die".
> > > > Ok. But if we want to use on-die ECC then you mean to say it is
> > > > mandatory to use
> > > micron_nand_read/write_page_on_die_ecc()?
> > >
> > > Absolutely, and if it doesn't work that means you driver does not
> > > implement raw accesses correctly, which means it's still buggy...
> > I agree. But let's say, if there is a limitation with the controller. Then it is must to have this
> check right?
> > I mean, for pl353 controller, we must clear the CS during the data
> > phase, hence we are splitting the Transfer in the pl353_read/write_page_raw().
> > +	pl353_nand_read_data_op(chip, buf, mtd->writesize, false);
> > +	p = chip->oob_poi;
> > +	pl353_nand_read_data_op(chip, p,
> > +				(mtd->oobsize -
> > +				PL353_NAND_LAST_TRANSFER_LENGTH), false);
> > +	p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
> > +	xnfc->dataphase_addrflags |= PL353_NAND_CLEAR_CS;
> > +	pl353_nand_read_data_op(chip, p, PL353_NAND_LAST_TRANSFER_LENGTH,
> > +				false);
> > As the above sequence is needed even for raw access, PL353 is unable to use the on_die_page
> reads.
> 
> This "de-assert CS on last access" logic should be done in the
> exec_op() implementation. I also wonder how that works for operations that don't have data
> cycles. Oh, BTW, most chips are CE-don't-care, which means you can assert/de-assert CS on
> each read_data_op() without any issues.
Yes, we can assert/de-assert CS on each read/write_data_op().
But what about transfer length splitting?
+	p = chip->oob_poi;
+	pl353_nand_read_data_op(chip, p,
+				(mtd->oobsize -
+				PL353_NAND_LAST_TRANSFER_LENGTH), false);
+	p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
This should be done as a part of pl353_raw_read/write() right?

Thanks,
Naga Sureshkumar Relli
Boris Brezillon June 26, 2019, 12:20 p.m. UTC | #8
On Wed, 26 Jun 2019 12:12:47 +0000
Naga Sureshkumar Relli <nagasure@xilinx.com> wrote:

> Hi Boris,
> 
> > -----Original Message-----
> > From: Boris Brezillon <boris.brezillon@collabora.com>
> > Sent: Wednesday, June 26, 2019 5:34 PM
> > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de; richard@nod.at;
> > dwmw2@infradead.org; computersforpeace@gmail.com; marek.vasut@gmail.com;
> > vigneshr@ti.com; bbrezillon@kernel.org; yamada.masahiro@socionext.com; linux-
> > mtd@lists.infradead.org; linux-kernel@vger.kernel.org
> > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not over write
> > driver's read_page()/write_page()
> > 
> > On Wed, 26 Jun 2019 11:51:12 +0000
> > Naga Sureshkumar Relli <nagasure@xilinx.com> wrote:
> >   
> > > Hi Boris,
> > >  
> > > > -----Original Message-----
> > > > From: Boris Brezillon <boris.brezillon@collabora.com>
> > > > Sent: Wednesday, June 26, 2019 4:57 PM
> > > > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > > > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de;
> > > > richard@nod.at; dwmw2@infradead.org; computersforpeace@gmail.com;
> > > > marek.vasut@gmail.com; vigneshr@ti.com; bbrezillon@kernel.org;
> > > > yamada.masahiro@socionext.com; linux- mtd@lists.infradead.org;
> > > > linux-kernel@vger.kernel.org
> > > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not
> > > > over write driver's read_page()/write_page()
> > > >
> > > > On Wed, 26 Jun 2019 11:22:33 +0000
> > > > Naga Sureshkumar Relli <nagasure@xilinx.com> wrote:
> > > >  
> > > > > Hi Boris,
> > > > >  
> > > > > > -----Original Message-----
> > > > > > From: Boris Brezillon <boris.brezillon@collabora.com>
> > > > > > Sent: Wednesday, June 26, 2019 12:18 PM
> > > > > > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > > > > > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de;
> > > > > > richard@nod.at; dwmw2@infradead.org;
> > > > > > computersforpeace@gmail.com; marek.vasut@gmail.com;
> > > > > > vigneshr@ti.com; bbrezillon@kernel.org;
> > > > > > yamada.masahiro@socionext.com; linux- mtd@lists.infradead.org;
> > > > > > linux-kernel@vger.kernel.org
> > > > > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do
> > > > > > not over write driver's read_page()/write_page()
> > > > > >
> > > > > > On Mon, 24 Jun 2019 22:46:29 -0600 Naga Sureshkumar Relli
> > > > > > <naga.sureshkumar.relli@xilinx.com> wrote:
> > > > > >  
> > > > > > > Add check before assigning chip->ecc.read_page() and
> > > > > > > chip->ecc.write_page()
> > > > > > >
> > > > > > > Signed-off-by: Naga Sureshkumar Relli
> > > > > > > <naga.sureshkumar.relli@xilinx.com>
> > > > > > > ---
> > > > > > >  drivers/mtd/nand/raw/nand_micron.c | 7 +++++--
> > > > > > >  1 file changed, 5 insertions(+), 2 deletions(-)
> > > > > > >
> > > > > > > diff --git a/drivers/mtd/nand/raw/nand_micron.c
> > > > > > > b/drivers/mtd/nand/raw/nand_micron.c
> > > > > > > index cbd4f09ac178..565f2696c747 100644
> > > > > > > --- a/drivers/mtd/nand/raw/nand_micron.c
> > > > > > > +++ b/drivers/mtd/nand/raw/nand_micron.c
> > > > > > > @@ -500,8 +500,11 @@ static int micron_nand_init(struct nand_chip *chip)
> > > > > > >  		chip->ecc.size = 512;
> > > > > > >  		chip->ecc.strength = chip->base.eccreq.strength;
> > > > > > >  		chip->ecc.algo = NAND_ECC_BCH;
> > > > > > > -		chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > > > > > > -		chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
> > > > > > > +		if (!chip->ecc.read_page)
> > > > > > > +			chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > > > > > > +
> > > > > > > +		if (!chip->ecc.write_page)
> > > > > > > +			chip->ecc.write_page = micron_nand_write_page_on_die_ecc;  
> > > > > >
> > > > > > That's wrong, if you don't want on-die ECC to be used, simply
> > > > > > don't set nand-ecc-mode to "on- die".  
> > > > > Ok. But if we want to use on-die ECC then you mean to say it is
> > > > > mandatory to use  
> > > > micron_nand_read/write_page_on_die_ecc()?
> > > >
> > > > Absolutely, and if it doesn't work that means you driver does not
> > > > implement raw accesses correctly, which means it's still buggy...  
> > > I agree. But let's say, if there is a limitation with the controller. Then it is must to have this  
> > check right?  
> > > I mean, for pl353 controller, we must clear the CS during the data
> > > phase, hence we are splitting the Transfer in the pl353_read/write_page_raw().
> > > +	pl353_nand_read_data_op(chip, buf, mtd->writesize, false);
> > > +	p = chip->oob_poi;
> > > +	pl353_nand_read_data_op(chip, p,
> > > +				(mtd->oobsize -
> > > +				PL353_NAND_LAST_TRANSFER_LENGTH), false);
> > > +	p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
> > > +	xnfc->dataphase_addrflags |= PL353_NAND_CLEAR_CS;
> > > +	pl353_nand_read_data_op(chip, p, PL353_NAND_LAST_TRANSFER_LENGTH,
> > > +				false);
> > > As the above sequence is needed even for raw access, PL353 is unable to use the on_die_page  
> > reads.
> > 
> > This "de-assert CS on last access" logic should be done in the
> > exec_op() implementation. I also wonder how that works for operations that don't have data
> > cycles. Oh, BTW, most chips are CE-don't-care, which means you can assert/de-assert CS on
> > each read_data_op() without any issues.  
> Yes, we can assert/de-assert CS on each read/write_data_op().
> But what about transfer length splitting?
> +	p = chip->oob_poi;
> +	pl353_nand_read_data_op(chip, p,
> +				(mtd->oobsize -
> +				PL353_NAND_LAST_TRANSFER_LENGTH), false);
> +	p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
> This should be done as a part of pl353_raw_read/write() right?

Are you sure you need to do that, and if that's the case, do you have
an idea why this is needed? Is this "read last 4 bytes separately"
thing is needed, I suspect it's needed for any kind of input-data
cycles, not just page reads.
Naga Sureshkumar Relli June 26, 2019, 12:33 p.m. UTC | #9
Hi Boris,

> -----Original Message-----
> From: Boris Brezillon <boris.brezillon@collabora.com>
> Sent: Wednesday, June 26, 2019 5:50 PM
> To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de; richard@nod.at;
> dwmw2@infradead.org; computersforpeace@gmail.com; marek.vasut@gmail.com;
> vigneshr@ti.com; bbrezillon@kernel.org; yamada.masahiro@socionext.com; linux-
> mtd@lists.infradead.org; linux-kernel@vger.kernel.org
> Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not over write
> driver's read_page()/write_page()
> 
> On Wed, 26 Jun 2019 12:12:47 +0000
> Naga Sureshkumar Relli <nagasure@xilinx.com> wrote:
> 
> > Hi Boris,
> >
> > > -----Original Message-----
> > > From: Boris Brezillon <boris.brezillon@collabora.com>
> > > Sent: Wednesday, June 26, 2019 5:34 PM
> > > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de;
> > > richard@nod.at; dwmw2@infradead.org; computersforpeace@gmail.com;
> > > marek.vasut@gmail.com; vigneshr@ti.com; bbrezillon@kernel.org;
> > > yamada.masahiro@socionext.com; linux- mtd@lists.infradead.org;
> > > linux-kernel@vger.kernel.org
> > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not
> > > over write driver's read_page()/write_page()
> > >
> > > On Wed, 26 Jun 2019 11:51:12 +0000
> > > Naga Sureshkumar Relli <nagasure@xilinx.com> wrote:
> > >
> > > > Hi Boris,
> > > >
> > > > > -----Original Message-----
> > > > > From: Boris Brezillon <boris.brezillon@collabora.com>
> > > > > Sent: Wednesday, June 26, 2019 4:57 PM
> > > > > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > > > > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de;
> > > > > richard@nod.at; dwmw2@infradead.org;
> > > > > computersforpeace@gmail.com; marek.vasut@gmail.com;
> > > > > vigneshr@ti.com; bbrezillon@kernel.org;
> > > > > yamada.masahiro@socionext.com; linux- mtd@lists.infradead.org;
> > > > > linux-kernel@vger.kernel.org
> > > > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do
> > > > > not over write driver's read_page()/write_page()
> > > > >
> > > > > On Wed, 26 Jun 2019 11:22:33 +0000 Naga Sureshkumar Relli
> > > > > <nagasure@xilinx.com> wrote:
> > > > >
> > > > > > Hi Boris,
> > > > > >
> > > > > > > -----Original Message-----
> > > > > > > From: Boris Brezillon <boris.brezillon@collabora.com>
> > > > > > > Sent: Wednesday, June 26, 2019 12:18 PM
> > > > > > > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > > > > > > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de;
> > > > > > > richard@nod.at; dwmw2@infradead.org;
> > > > > > > computersforpeace@gmail.com; marek.vasut@gmail.com;
> > > > > > > vigneshr@ti.com; bbrezillon@kernel.org;
> > > > > > > yamada.masahiro@socionext.com; linux-
> > > > > > > mtd@lists.infradead.org; linux-kernel@vger.kernel.org
> > > > > > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand:
> > > > > > > nand_micron: Do not over write driver's
> > > > > > > read_page()/write_page()
> > > > > > >
> > > > > > > On Mon, 24 Jun 2019 22:46:29 -0600 Naga Sureshkumar Relli
> > > > > > > <naga.sureshkumar.relli@xilinx.com> wrote:
> > > > > > >
> > > > > > > > Add check before assigning chip->ecc.read_page() and
> > > > > > > > chip->ecc.write_page()
> > > > > > > >
> > > > > > > > Signed-off-by: Naga Sureshkumar Relli
> > > > > > > > <naga.sureshkumar.relli@xilinx.com>
> > > > > > > > ---
> > > > > > > >  drivers/mtd/nand/raw/nand_micron.c | 7 +++++--
> > > > > > > >  1 file changed, 5 insertions(+), 2 deletions(-)
> > > > > > > >
> > > > > > > > diff --git a/drivers/mtd/nand/raw/nand_micron.c
> > > > > > > > b/drivers/mtd/nand/raw/nand_micron.c
> > > > > > > > index cbd4f09ac178..565f2696c747 100644
> > > > > > > > --- a/drivers/mtd/nand/raw/nand_micron.c
> > > > > > > > +++ b/drivers/mtd/nand/raw/nand_micron.c
> > > > > > > > @@ -500,8 +500,11 @@ static int micron_nand_init(struct nand_chip *chip)
> > > > > > > >  		chip->ecc.size = 512;
> > > > > > > >  		chip->ecc.strength = chip->base.eccreq.strength;
> > > > > > > >  		chip->ecc.algo = NAND_ECC_BCH;
> > > > > > > > -		chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > > > > > > > -		chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
> > > > > > > > +		if (!chip->ecc.read_page)
> > > > > > > > +			chip->ecc.read_page =
> > > > > > > > +micron_nand_read_page_on_die_ecc;
> > > > > > > > +
> > > > > > > > +		if (!chip->ecc.write_page)
> > > > > > > > +			chip->ecc.write_page =
> > > > > > > > +micron_nand_write_page_on_die_ecc;
> > > > > > >
> > > > > > > That's wrong, if you don't want on-die ECC to be used,
> > > > > > > simply don't set nand-ecc-mode to "on- die".
> > > > > > Ok. But if we want to use on-die ECC then you mean to say it
> > > > > > is mandatory to use
> > > > > micron_nand_read/write_page_on_die_ecc()?
> > > > >
> > > > > Absolutely, and if it doesn't work that means you driver does
> > > > > not implement raw accesses correctly, which means it's still buggy...
> > > > I agree. But let's say, if there is a limitation with the
> > > > controller. Then it is must to have this
> > > check right?
> > > > I mean, for pl353 controller, we must clear the CS during the data
> > > > phase, hence we are splitting the Transfer in the pl353_read/write_page_raw().
> > > > +	pl353_nand_read_data_op(chip, buf, mtd->writesize, false);
> > > > +	p = chip->oob_poi;
> > > > +	pl353_nand_read_data_op(chip, p,
> > > > +				(mtd->oobsize -
> > > > +				PL353_NAND_LAST_TRANSFER_LENGTH),
> false);
> > > > +	p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
> > > > +	xnfc->dataphase_addrflags |= PL353_NAND_CLEAR_CS;
> > > > +	pl353_nand_read_data_op(chip, p,
> PL353_NAND_LAST_TRANSFER_LENGTH,
> > > > +				false);
> > > > As the above sequence is needed even for raw access, PL353 is
> > > > unable to use the on_die_page
> > > reads.
> > >
> > > This "de-assert CS on last access" logic should be done in the
> > > exec_op() implementation. I also wonder how that works for
> > > operations that don't have data cycles. Oh, BTW, most chips are
> > > CE-don't-care, which means you can assert/de-assert CS on each read_data_op() without
> any issues.
> > Yes, we can assert/de-assert CS on each read/write_data_op().
> > But what about transfer length splitting?
> > +	p = chip->oob_poi;
> > +	pl353_nand_read_data_op(chip, p,
> > +				(mtd->oobsize -
> > +				PL353_NAND_LAST_TRANSFER_LENGTH), false);
> > +	p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
> > This should be done as a part of pl353_raw_read/write() right?
> 
> Are you sure you need to do that, and if that's the case, do you have an idea why this is needed?
> Is this "read last 4 bytes separately"
> thing is needed, I suspect it's needed for any kind of input-data cycles, not just page reads.
Yes. It is needed. This is Limitation in the HW, need to handle last 4 bytes separately for both page read/writes

Regards,
Naga Sureshkumar Relli
Naga Sureshkumar Relli July 8, 2019, 12:18 p.m. UTC | #10
Hi Boris,

> -----Original Message-----
> From: linux-mtd <linux-mtd-bounces@lists.infradead.org> On Behalf Of Naga Sureshkumar
> Relli
> Sent: Wednesday, June 26, 2019 6:04 PM
> To: Boris Brezillon <boris.brezillon@collabora.com>
> Cc: vigneshr@ti.com; bbrezillon@kernel.org; helmut.grohne@intenta.de; richard@nod.at;
> linux-kernel@vger.kernel.org; marek.vasut@gmail.com; yamada.masahiro@socionext.com;
> linux-mtd@lists.infradead.org; miquel.raynal@bootlin.com; computersforpeace@gmail.com;
> dwmw2@infradead.org
> Subject: RE: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not over write
> driver's read_page()/write_page()
> 
> Hi Boris,
> 
> > -----Original Message-----
> > From: Boris Brezillon <boris.brezillon@collabora.com>
> > Sent: Wednesday, June 26, 2019 5:50 PM
> > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de;
> > richard@nod.at; dwmw2@infradead.org; computersforpeace@gmail.com;
> > marek.vasut@gmail.com; vigneshr@ti.com; bbrezillon@kernel.org;
> > yamada.masahiro@socionext.com; linux- mtd@lists.infradead.org;
> > linux-kernel@vger.kernel.org
> > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do not
> > over write driver's read_page()/write_page()
> >
> > On Wed, 26 Jun 2019 12:12:47 +0000
> > Naga Sureshkumar Relli <nagasure@xilinx.com> wrote:
> >
> > > Hi Boris,
> > >
> > > > -----Original Message-----
> > > > From: Boris Brezillon <boris.brezillon@collabora.com>
> > > > Sent: Wednesday, June 26, 2019 5:34 PM
> > > > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > > > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de;
> > > > richard@nod.at; dwmw2@infradead.org; computersforpeace@gmail.com;
> > > > marek.vasut@gmail.com; vigneshr@ti.com; bbrezillon@kernel.org;
> > > > yamada.masahiro@socionext.com; linux- mtd@lists.infradead.org;
> > > > linux-kernel@vger.kernel.org
> > > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron: Do
> > > > not over write driver's read_page()/write_page()
> > > >
> > > > On Wed, 26 Jun 2019 11:51:12 +0000 Naga Sureshkumar Relli
> > > > <nagasure@xilinx.com> wrote:
> > > >
> > > > > Hi Boris,
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Boris Brezillon <boris.brezillon@collabora.com>
> > > > > > Sent: Wednesday, June 26, 2019 4:57 PM
> > > > > > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > > > > > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de;
> > > > > > richard@nod.at; dwmw2@infradead.org;
> > > > > > computersforpeace@gmail.com; marek.vasut@gmail.com;
> > > > > > vigneshr@ti.com; bbrezillon@kernel.org;
> > > > > > yamada.masahiro@socionext.com; linux- mtd@lists.infradead.org;
> > > > > > linux-kernel@vger.kernel.org
> > > > > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand: nand_micron:
> > > > > > Do not over write driver's read_page()/write_page()
> > > > > >
> > > > > > On Wed, 26 Jun 2019 11:22:33 +0000 Naga Sureshkumar Relli
> > > > > > <nagasure@xilinx.com> wrote:
> > > > > >
> > > > > > > Hi Boris,
> > > > > > >
> > > > > > > > -----Original Message-----
> > > > > > > > From: Boris Brezillon <boris.brezillon@collabora.com>
> > > > > > > > Sent: Wednesday, June 26, 2019 12:18 PM
> > > > > > > > To: Naga Sureshkumar Relli <nagasure@xilinx.com>
> > > > > > > > Cc: miquel.raynal@bootlin.com; helmut.grohne@intenta.de;
> > > > > > > > richard@nod.at; dwmw2@infradead.org;
> > > > > > > > computersforpeace@gmail.com; marek.vasut@gmail.com;
> > > > > > > > vigneshr@ti.com; bbrezillon@kernel.org;
> > > > > > > > yamada.masahiro@socionext.com; linux-
> > > > > > > > mtd@lists.infradead.org; linux-kernel@vger.kernel.org
> > > > > > > > Subject: Re: [LINUX PATCH v17 1/2] mtd: rawnand:
> > > > > > > > nand_micron: Do not over write driver's
> > > > > > > > read_page()/write_page()
> > > > > > > >
> > > > > > > > On Mon, 24 Jun 2019 22:46:29 -0600 Naga Sureshkumar Relli
> > > > > > > > <naga.sureshkumar.relli@xilinx.com> wrote:
> > > > > > > >
> > > > > > > > > Add check before assigning chip->ecc.read_page() and
> > > > > > > > > chip->ecc.write_page()
> > > > > > > > >
> > > > > > > > > Signed-off-by: Naga Sureshkumar Relli
> > > > > > > > > <naga.sureshkumar.relli@xilinx.com>
> > > > > > > > > ---
> > > > > > > > >  drivers/mtd/nand/raw/nand_micron.c | 7 +++++--
> > > > > > > > >  1 file changed, 5 insertions(+), 2 deletions(-)
> > > > > > > > >
> > > > > > > > > diff --git a/drivers/mtd/nand/raw/nand_micron.c
> > > > > > > > > b/drivers/mtd/nand/raw/nand_micron.c
> > > > > > > > > index cbd4f09ac178..565f2696c747 100644
> > > > > > > > > --- a/drivers/mtd/nand/raw/nand_micron.c
> > > > > > > > > +++ b/drivers/mtd/nand/raw/nand_micron.c
> > > > > > > > > @@ -500,8 +500,11 @@ static int micron_nand_init(struct nand_chip
> *chip)
> > > > > > > > >  		chip->ecc.size = 512;
> > > > > > > > >  		chip->ecc.strength = chip->base.eccreq.strength;
> > > > > > > > >  		chip->ecc.algo = NAND_ECC_BCH;
> > > > > > > > > -		chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
> > > > > > > > > -		chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
> > > > > > > > > +		if (!chip->ecc.read_page)
> > > > > > > > > +			chip->ecc.read_page =
> > > > > > > > > +micron_nand_read_page_on_die_ecc;
> > > > > > > > > +
> > > > > > > > > +		if (!chip->ecc.write_page)
> > > > > > > > > +			chip->ecc.write_page =
> > > > > > > > > +micron_nand_write_page_on_die_ecc;
> > > > > > > >
> > > > > > > > That's wrong, if you don't want on-die ECC to be used,
> > > > > > > > simply don't set nand-ecc-mode to "on- die".
> > > > > > > Ok. But if we want to use on-die ECC then you mean to say it
> > > > > > > is mandatory to use
> > > > > > micron_nand_read/write_page_on_die_ecc()?
> > > > > >
> > > > > > Absolutely, and if it doesn't work that means you driver does
> > > > > > not implement raw accesses correctly, which means it's still buggy...
> > > > > I agree. But let's say, if there is a limitation with the
> > > > > controller. Then it is must to have this
> > > > check right?
> > > > > I mean, for pl353 controller, we must clear the CS during the
> > > > > data phase, hence we are splitting the Transfer in the pl353_read/write_page_raw().
> > > > > +	pl353_nand_read_data_op(chip, buf, mtd->writesize, false);
> > > > > +	p = chip->oob_poi;
> > > > > +	pl353_nand_read_data_op(chip, p,
> > > > > +				(mtd->oobsize -
> > > > > +				PL353_NAND_LAST_TRANSFER_LENGTH),
> > false);
> > > > > +	p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
> > > > > +	xnfc->dataphase_addrflags |= PL353_NAND_CLEAR_CS;
> > > > > +	pl353_nand_read_data_op(chip, p,
> > PL353_NAND_LAST_TRANSFER_LENGTH,
> > > > > +				false);
> > > > > As the above sequence is needed even for raw access, PL353 is
> > > > > unable to use the on_die_page
> > > > reads.
> > > >
> > > > This "de-assert CS on last access" logic should be done in the
> > > > exec_op() implementation. I also wonder how that works for
> > > > operations that don't have data cycles. Oh, BTW, most chips are
> > > > CE-don't-care, which means you can assert/de-assert CS on each
> > > > read_data_op() without
> > any issues.
> > > Yes, we can assert/de-assert CS on each read/write_data_op().
> > > But what about transfer length splitting?
> > > +	p = chip->oob_poi;
> > > +	pl353_nand_read_data_op(chip, p,
> > > +				(mtd->oobsize -
> > > +				PL353_NAND_LAST_TRANSFER_LENGTH), false);
> > > +	p += (mtd->oobsize - PL353_NAND_LAST_TRANSFER_LENGTH);
> > > This should be done as a part of pl353_raw_read/write() right?
> >
> > Are you sure you need to do that, and if that's the case, do you have an idea why this is
> needed?
> > Is this "read last 4 bytes separately"
> > thing is needed, I suspect it's needed for any kind of input-data cycles, not just page reads.
> Yes. It is needed. This is Limitation in the HW, need to handle last 4 bytes separately for both
> page read/writes
Just wanted to know, is this fix OK?

Regards,
Naga Sureshkumar Relli
> 
> Regards,
> Naga Sureshkumar Relli
> 
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/

Patch
diff mbox series

diff --git a/drivers/mtd/nand/raw/nand_micron.c b/drivers/mtd/nand/raw/nand_micron.c
index cbd4f09ac178..565f2696c747 100644
--- a/drivers/mtd/nand/raw/nand_micron.c
+++ b/drivers/mtd/nand/raw/nand_micron.c
@@ -500,8 +500,11 @@  static int micron_nand_init(struct nand_chip *chip)
 		chip->ecc.size = 512;
 		chip->ecc.strength = chip->base.eccreq.strength;
 		chip->ecc.algo = NAND_ECC_BCH;
-		chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
-		chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
+		if (!chip->ecc.read_page)
+			chip->ecc.read_page = micron_nand_read_page_on_die_ecc;
+
+		if (!chip->ecc.write_page)
+			chip->ecc.write_page = micron_nand_write_page_on_die_ecc;
 
 		if (ondie == MICRON_ON_DIE_MANDATORY) {
 			chip->ecc.read_page_raw = nand_read_page_raw_notsupp;