[PATCH 1/2] dt-bindings: mtd: gpmi-nand: specify fsl,use-minimum-ecc behavior

[PATCH 1/2] dt-bindings: mtd: gpmi-nand: specify fsl,use-minimum-ecc behavior

[Stefan Agner]

The dt property fsl,use-minimum-ecc requires a NAND chip to
provide a ECC strength/step size, otherwise the driver fails
to probe. This is by design to avoid that the driver uses a
fallback and later changes ECC parameters due to additionion
of a NAND chip driver. Document the current behavior.

Signed-off-by: Stefan Agner <stefan@agner.ch>
---
 Documentation/devicetree/bindings/mtd/gpmi-nand.txt | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
index b289ef3c1b7e..eb2d9919d063 100644
--- a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
+++ b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
@@ -34,9 +34,8 @@ Optional properties:
                        automatically discoverable for some flash
                        (e.g., according to the ONFI standard).
                        However, note that if this strength is not
-                       discoverable or this property is not enabled,
-                       the software may chooses an implementation-defined
-                       ECC scheme.
+                       discoverable the driver will fail probing with
+                       an error.
   - fsl,no-blockmark-swap: Don't swap the bad block marker from the OOB
                        area with the byte in the data area but rely on the
                        flash based BBT for identifying bad blocks.
-- 
2.16.1

[PATCH 2/2] mtd: nand: gpmi: add support for specific ECC strength

[Stefan Agner]

Add support for specified ECC strength/size using device tree
properties nand-ecc-strength/nand-ecc-step-size.

Signed-off-by: Stefan Agner <stefan@agner.ch>
---
 .../devicetree/bindings/mtd/gpmi-nand.txt          |  5 ++++
 drivers/mtd/nand/gpmi-nand/gpmi-nand.c             | 29 ++++++++++++++--------
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
index eb2d9919d063..ea6e9b735160 100644
--- a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
+++ b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
@@ -46,6 +46,11 @@ Optional properties:
                        partitions written from Linux with this feature
                        turned on may not be accessible by the BootROM
                        code.
+  - nand-ecc-strength: integer representing the number of bits to correct
+                       per ECC step. Needs to be a multiple of 2.
+  - nand-ecc-step-size: integer representing the number of data bytes
+                       that are covered by a single ECC step. The driver
+                       supports 512 and 1024.
 
 The device tree may optionally contain sub-nodes describing partitions of the
 address space. See partition.txt for more detail.
diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
index 50f8d4a1b983..8cb378358e11 100644
--- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
+++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
@@ -198,17 +198,15 @@ static inline bool gpmi_check_ecc(struct gpmi_nand_data *this)
  *
  * We may have available oob space in this case.
  */
-static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
+static int set_geometry_by_ecc_info(struct gpmi_nand_data *this,
+			unsigned int ecc_strength, unsigned int ecc_step)
 {
 	struct bch_geometry *geo = &this->bch_geometry;
 	struct nand_chip *chip = &this->nand;
 	struct mtd_info *mtd = nand_to_mtd(chip);
 	unsigned int block_mark_bit_offset;
 
-	if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
-		return -EINVAL;
-
-	switch (chip->ecc_step_ds) {
+	switch (ecc_step) {
 	case SZ_512:
 		geo->gf_len = 13;
 		break;
@@ -221,8 +219,8 @@ static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
 			chip->ecc_strength_ds, chip->ecc_step_ds);
 		return -EINVAL;
 	}
-	geo->ecc_chunk_size = chip->ecc_step_ds;
-	geo->ecc_strength = round_up(chip->ecc_strength_ds, 2);
+	geo->ecc_chunk_size = ecc_step;
+	geo->ecc_strength = round_up(ecc_strength, 2);
 	if (!gpmi_check_ecc(this))
 		return -EINVAL;
 
@@ -230,7 +228,7 @@ static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
 	if (geo->ecc_chunk_size < mtd->oobsize) {
 		dev_err(this->dev,
 			"unsupported nand chip. ecc size: %d, oob size : %d\n",
-			chip->ecc_step_ds, mtd->oobsize);
+			ecc_step, mtd->oobsize);
 		return -EINVAL;
 	}
 
@@ -423,9 +421,20 @@ static int legacy_set_geometry(struct gpmi_nand_data *this)
 
 int common_nfc_set_geometry(struct gpmi_nand_data *this)
 {
+	struct nand_chip *chip = &this->nand;
+
+	if (chip->ecc.strength > 0 && chip->ecc.size > 0)
+		return set_geometry_by_ecc_info(this, chip->ecc.strength,
+						chip->ecc.size);
+
 	if ((of_property_read_bool(this->dev->of_node, "fsl,use-minimum-ecc"))
-				|| legacy_set_geometry(this))
-		return set_geometry_by_ecc_info(this);
+				|| legacy_set_geometry(this)) {
+		if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
+			return -EINVAL;
+
+		return set_geometry_by_ecc_info(this, chip->ecc_strength_ds,
+						chip->ecc_step_ds);
+	}
 
 	return 0;
 }
-- 
2.16.1

Re: [PATCH 2/2] mtd: nand: gpmi: add support for specific ECC strength

[Boris Brezillon]

On Tue,  6 Feb 2018 18:40:21 +0100
Stefan Agner <stefan@agner.ch> wrote:

> Add support for specified ECC strength/size using device tree
> properties nand-ecc-strength/nand-ecc-step-size.
> 
> Signed-off-by: Stefan Agner <stefan@agner.ch>
> ---
>  .../devicetree/bindings/mtd/gpmi-nand.txt          |  5 ++++

I don't care that much, but I know DT maintainers like to have DT
bindings changes placed in a separate patch.

>  drivers/mtd/nand/gpmi-nand/gpmi-nand.c             | 29 ++++++++++++++--------
>  2 files changed, 24 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
> index eb2d9919d063..ea6e9b735160 100644
> --- a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
> +++ b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
> @@ -46,6 +46,11 @@ Optional properties:
>                         partitions written from Linux with this feature
>                         turned on may not be accessible by the BootROM
>                         code.
> +  - nand-ecc-strength: integer representing the number of bits to correct
> +                       per ECC step. Needs to be a multiple of 2.
> +  - nand-ecc-step-size: integer representing the number of data bytes
> +                       that are covered by a single ECC step. The driver
> +                       supports 512 and 1024.
>  
>  The device tree may optionally contain sub-nodes describing partitions of the
>  address space. See partition.txt for more detail.
> diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> index 50f8d4a1b983..8cb378358e11 100644
> --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> @@ -198,17 +198,15 @@ static inline bool gpmi_check_ecc(struct gpmi_nand_data *this)
>   *
>   * We may have available oob space in this case.
>   */
> -static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
> +static int set_geometry_by_ecc_info(struct gpmi_nand_data *this,
> +			unsigned int ecc_strength, unsigned int ecc_step)
>  {
>  	struct bch_geometry *geo = &this->bch_geometry;
>  	struct nand_chip *chip = &this->nand;
>  	struct mtd_info *mtd = nand_to_mtd(chip);
>  	unsigned int block_mark_bit_offset;
>  
> -	if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
> -		return -EINVAL;
> -
> -	switch (chip->ecc_step_ds) {
> +	switch (ecc_step) {
>  	case SZ_512:
>  		geo->gf_len = 13;
>  		break;
> @@ -221,8 +219,8 @@ static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
>  			chip->ecc_strength_ds, chip->ecc_step_ds);
>  		return -EINVAL;
>  	}
> -	geo->ecc_chunk_size = chip->ecc_step_ds;
> -	geo->ecc_strength = round_up(chip->ecc_strength_ds, 2);
> +	geo->ecc_chunk_size = ecc_step;
> +	geo->ecc_strength = round_up(ecc_strength, 2);
>  	if (!gpmi_check_ecc(this))
>  		return -EINVAL;
>  
> @@ -230,7 +228,7 @@ static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
>  	if (geo->ecc_chunk_size < mtd->oobsize) {
>  		dev_err(this->dev,
>  			"unsupported nand chip. ecc size: %d, oob size : %d\n",
> -			chip->ecc_step_ds, mtd->oobsize);
> +			ecc_step, mtd->oobsize);
>  		return -EINVAL;
>  	}
>  
> @@ -423,9 +421,20 @@ static int legacy_set_geometry(struct gpmi_nand_data *this)
>  
>  int common_nfc_set_geometry(struct gpmi_nand_data *this)
>  {
> +	struct nand_chip *chip = &this->nand;
> +
> +	if (chip->ecc.strength > 0 && chip->ecc.size > 0)
> +		return set_geometry_by_ecc_info(this, chip->ecc.strength,
> +						chip->ecc.size);
> +
>  	if ((of_property_read_bool(this->dev->of_node, "fsl,use-minimum-ecc"))
> -				|| legacy_set_geometry(this))
> -		return set_geometry_by_ecc_info(this);
> +				|| legacy_set_geometry(this)) {
> +		if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
> +			return -EINVAL;
> +
> +		return set_geometry_by_ecc_info(this, chip->ecc_strength_ds,
> +						chip->ecc_step_ds);
> +	}
>  
>  	return 0;
>  }

Both patches look good to me. Han, could review them and add your Ack
if you're happy with the changes.

Thanks,

Boris

-- 
Boris Brezillon, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
http://bootlin.com

Re: [PATCH 2/2] mtd: nand: gpmi: add support for specific ECC strength

[Boris Brezillon]

On Tue,  6 Feb 2018 18:40:21 +0100
Stefan Agner <stefan@agner.ch> wrote:

> Add support for specified ECC strength/size using device tree
> properties nand-ecc-strength/nand-ecc-step-size.
> 
> Signed-off-by: Stefan Agner <stefan@agner.ch>
> ---
>  .../devicetree/bindings/mtd/gpmi-nand.txt          |  5 ++++
>  drivers/mtd/nand/gpmi-nand/gpmi-nand.c             | 29 ++++++++++++++--------
>  2 files changed, 24 insertions(+), 10 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
> index eb2d9919d063..ea6e9b735160 100644
> --- a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
> +++ b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
> @@ -46,6 +46,11 @@ Optional properties:
>                         partitions written from Linux with this feature
>                         turned on may not be accessible by the BootROM
>                         code.
> +  - nand-ecc-strength: integer representing the number of bits to correct
> +                       per ECC step. Needs to be a multiple of 2.
> +  - nand-ecc-step-size: integer representing the number of data bytes
> +                       that are covered by a single ECC step. The driver
> +                       supports 512 and 1024.
>  
>  The device tree may optionally contain sub-nodes describing partitions of the
>  address space. See partition.txt for more detail.
> diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> index 50f8d4a1b983..8cb378358e11 100644
> --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> @@ -198,17 +198,15 @@ static inline bool gpmi_check_ecc(struct gpmi_nand_data *this)
>   *
>   * We may have available oob space in this case.
>   */
> -static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
> +static int set_geometry_by_ecc_info(struct gpmi_nand_data *this,
> +			unsigned int ecc_strength, unsigned int ecc_step)

Nitpick: if you send a new version, could you align the second
parameter on the open parenthesis?

>  {
>  	struct bch_geometry *geo = &this->bch_geometry;
>  	struct nand_chip *chip = &this->nand;
>  	struct mtd_info *mtd = nand_to_mtd(chip);
>  	unsigned int block_mark_bit_offset;
>  
> -	if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
> -		return -EINVAL;
> -
> -	switch (chip->ecc_step_ds) {
> +	switch (ecc_step) {
>  	case SZ_512:
>  		geo->gf_len = 13;
>  		break;
> @@ -221,8 +219,8 @@ static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
>  			chip->ecc_strength_ds, chip->ecc_step_ds);
>  		return -EINVAL;
>  	}
> -	geo->ecc_chunk_size = chip->ecc_step_ds;
> -	geo->ecc_strength = round_up(chip->ecc_strength_ds, 2);
> +	geo->ecc_chunk_size = ecc_step;
> +	geo->ecc_strength = round_up(ecc_strength, 2);
>  	if (!gpmi_check_ecc(this))
>  		return -EINVAL;
>  
> @@ -230,7 +228,7 @@ static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
>  	if (geo->ecc_chunk_size < mtd->oobsize) {
>  		dev_err(this->dev,
>  			"unsupported nand chip. ecc size: %d, oob size : %d\n",
> -			chip->ecc_step_ds, mtd->oobsize);
> +			ecc_step, mtd->oobsize);
>  		return -EINVAL;
>  	}
>  
> @@ -423,9 +421,20 @@ static int legacy_set_geometry(struct gpmi_nand_data *this)
>  
>  int common_nfc_set_geometry(struct gpmi_nand_data *this)
>  {
> +	struct nand_chip *chip = &this->nand;
> +
> +	if (chip->ecc.strength > 0 && chip->ecc.size > 0)
> +		return set_geometry_by_ecc_info(this, chip->ecc.strength,
> +						chip->ecc.size);
> +
>  	if ((of_property_read_bool(this->dev->of_node, "fsl,use-minimum-ecc"))
> -				|| legacy_set_geometry(this))
> -		return set_geometry_by_ecc_info(this);
> +				|| legacy_set_geometry(this)) {
> +		if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
> +			return -EINVAL;
> +
> +		return set_geometry_by_ecc_info(this, chip->ecc_strength_ds,
> +						chip->ecc_step_ds);
> +	}
>  
>  	return 0;
>  }



-- 
Boris Brezillon, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
http://bootlin.com

Re: [PATCH 2/2] mtd: nand: gpmi: add support for specific ECC strength

[Han Xu]

On 02/06/2018 11:40 AM, Stefan Agner wrote:
> Add support for specified ECC strength/size using device tree
> properties nand-ecc-strength/nand-ecc-step-size.
>
> Signed-off-by: Stefan Agner <stefan@agner.ch>
> ---
>   .../devicetree/bindings/mtd/gpmi-nand.txt          |  5 ++++
>   drivers/mtd/nand/gpmi-nand/gpmi-nand.c             | 29 ++++++++++++++--------
>   2 files changed, 24 insertions(+), 10 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
> index eb2d9919d063..ea6e9b735160 100644
> --- a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
> +++ b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
> @@ -46,6 +46,11 @@ Optional properties:
>                          partitions written from Linux with this feature
>                          turned on may not be accessible by the BootROM
>                          code.
> +  - nand-ecc-strength: integer representing the number of bits to correct
> +                       per ECC step. Needs to be a multiple of 2.
> +  - nand-ecc-step-size: integer representing the number of data bytes
> +                       that are covered by a single ECC step. The driver
> +                       supports 512 and 1024.
>   
>   The device tree may optionally contain sub-nodes describing partitions of the
>   address space. See partition.txt for more detail.
> diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> index 50f8d4a1b983..8cb378358e11 100644
> --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> @@ -198,17 +198,15 @@ static inline bool gpmi_check_ecc(struct gpmi_nand_data *this)
>    *
>    * We may have available oob space in this case.
>    */
> -static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
> +static int set_geometry_by_ecc_info(struct gpmi_nand_data *this,
> +			unsigned int ecc_strength, unsigned int ecc_step)
>   {
>   	struct bch_geometry *geo = &this->bch_geometry;
>   	struct nand_chip *chip = &this->nand;
>   	struct mtd_info *mtd = nand_to_mtd(chip);
>   	unsigned int block_mark_bit_offset;
>   
> -	if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
> -		return -EINVAL;
> -
> -	switch (chip->ecc_step_ds) {
> +	switch (ecc_step) {
>   	case SZ_512:
>   		geo->gf_len = 13;
>   		break;
> @@ -221,8 +219,8 @@ static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
>   			chip->ecc_strength_ds, chip->ecc_step_ds);
>   		return -EINVAL;
>   	}
> -	geo->ecc_chunk_size = chip->ecc_step_ds;
> -	geo->ecc_strength = round_up(chip->ecc_strength_ds, 2);
> +	geo->ecc_chunk_size = ecc_step;
> +	geo->ecc_strength = round_up(ecc_strength, 2);
>   	if (!gpmi_check_ecc(this))
>   		return -EINVAL;
>   
> @@ -230,7 +228,7 @@ static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
>   	if (geo->ecc_chunk_size < mtd->oobsize) {
>   		dev_err(this->dev,
>   			"unsupported nand chip. ecc size: %d, oob size : %d\n",
> -			chip->ecc_step_ds, mtd->oobsize);
> +			ecc_step, mtd->oobsize);
>   		return -EINVAL;
>   	}
>   
> @@ -423,9 +421,20 @@ static int legacy_set_geometry(struct gpmi_nand_data *this)
>   
>   int common_nfc_set_geometry(struct gpmi_nand_data *this)
>   {
> +	struct nand_chip *chip = &this->nand;
> +
> +	if (chip->ecc.strength > 0 && chip->ecc.size > 0)
> +		return set_geometry_by_ecc_info(this, chip->ecc.strength,
> +						chip->ecc.size);
> +

I was wondering how to keep, let's say u-boot, and kernel ecc setting 
aligned, if users can specify the strength and step_ds in DT? Did u-boot 
enable to get these parameters from DT?
>   	if ((of_property_read_bool(this->dev->of_node, "fsl,use-minimum-ecc"))
> -				|| legacy_set_geometry(this))
> -		return set_geometry_by_ecc_info(this);
> +				|| legacy_set_geometry(this)) {
> +		if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
> +			return -EINVAL;
> +
> +		return set_geometry_by_ecc_info(this, chip->ecc_strength_ds,
> +						chip->ecc_step_ds);
> +	}
>   
>   	return 0;
>   }

Re: [PATCH 2/2] mtd: nand: gpmi: add support for specific ECC strength

[Boris Brezillon]

On Wed, 14 Feb 2018 16:28:36 +0000
Han Xu <han.xu@nxp.com> wrote:

> On 02/06/2018 11:40 AM, Stefan Agner wrote:
> > Add support for specified ECC strength/size using device tree
> > properties nand-ecc-strength/nand-ecc-step-size.
> >
> > Signed-off-by: Stefan Agner <stefan@agner.ch>
> > ---
> >   .../devicetree/bindings/mtd/gpmi-nand.txt          |  5 ++++
> >   drivers/mtd/nand/gpmi-nand/gpmi-nand.c             | 29 ++++++++++++++--------
> >   2 files changed, 24 insertions(+), 10 deletions(-)
> >
> > diff --git a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
> > index eb2d9919d063..ea6e9b735160 100644
> > --- a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
> > +++ b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
> > @@ -46,6 +46,11 @@ Optional properties:
> >                          partitions written from Linux with this feature
> >                          turned on may not be accessible by the BootROM
> >                          code.
> > +  - nand-ecc-strength: integer representing the number of bits to correct
> > +                       per ECC step. Needs to be a multiple of 2.
> > +  - nand-ecc-step-size: integer representing the number of data bytes
> > +                       that are covered by a single ECC step. The driver
> > +                       supports 512 and 1024.
> >   
> >   The device tree may optionally contain sub-nodes describing partitions of the
> >   address space. See partition.txt for more detail.
> > diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> > index 50f8d4a1b983..8cb378358e11 100644
> > --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> > +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> > @@ -198,17 +198,15 @@ static inline bool gpmi_check_ecc(struct gpmi_nand_data *this)
> >    *
> >    * We may have available oob space in this case.
> >    */
> > -static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
> > +static int set_geometry_by_ecc_info(struct gpmi_nand_data *this,
> > +			unsigned int ecc_strength, unsigned int ecc_step)
> >   {
> >   	struct bch_geometry *geo = &this->bch_geometry;
> >   	struct nand_chip *chip = &this->nand;
> >   	struct mtd_info *mtd = nand_to_mtd(chip);
> >   	unsigned int block_mark_bit_offset;
> >   
> > -	if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
> > -		return -EINVAL;
> > -
> > -	switch (chip->ecc_step_ds) {
> > +	switch (ecc_step) {
> >   	case SZ_512:
> >   		geo->gf_len = 13;
> >   		break;
> > @@ -221,8 +219,8 @@ static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
> >   			chip->ecc_strength_ds, chip->ecc_step_ds);
> >   		return -EINVAL;
> >   	}
> > -	geo->ecc_chunk_size = chip->ecc_step_ds;
> > -	geo->ecc_strength = round_up(chip->ecc_strength_ds, 2);
> > +	geo->ecc_chunk_size = ecc_step;
> > +	geo->ecc_strength = round_up(ecc_strength, 2);
> >   	if (!gpmi_check_ecc(this))
> >   		return -EINVAL;
> >   
> > @@ -230,7 +228,7 @@ static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
> >   	if (geo->ecc_chunk_size < mtd->oobsize) {
> >   		dev_err(this->dev,
> >   			"unsupported nand chip. ecc size: %d, oob size : %d\n",
> > -			chip->ecc_step_ds, mtd->oobsize);
> > +			ecc_step, mtd->oobsize);
> >   		return -EINVAL;
> >   	}
> >   
> > @@ -423,9 +421,20 @@ static int legacy_set_geometry(struct gpmi_nand_data *this)
> >   
> >   int common_nfc_set_geometry(struct gpmi_nand_data *this)
> >   {
> > +	struct nand_chip *chip = &this->nand;
> > +
> > +	if (chip->ecc.strength > 0 && chip->ecc.size > 0)
> > +		return set_geometry_by_ecc_info(this, chip->ecc.strength,
> > +						chip->ecc.size);
> > +  
> 
> I was wondering how to keep, let's say u-boot, and kernel ecc setting 
> aligned, if users can specify the strength and step_ds in DT? Did u-boot 
> enable to get these parameters from DT?

Both u-boot and Linux have to support using strength/step information
passed through the DT before you can start patching dts files. Anyway,
users will have to change their DT (add the nand-ecc-strength/step-size
properties) to use this feature, so they should quickly notice that
something is going wrong and update their bootloader or drop those
nand-ecc-xxx props.

> >   	if ((of_property_read_bool(this->dev->of_node, "fsl,use-minimum-ecc"))
> > -				|| legacy_set_geometry(this))
> > -		return set_geometry_by_ecc_info(this);
> > +				|| legacy_set_geometry(this)) {
> > +		if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
> > +			return -EINVAL;
> > +
> > +		return set_geometry_by_ecc_info(this, chip->ecc_strength_ds,
> > +						chip->ecc_step_ds);
> > +	}
> >   
> >   	return 0;
> >   }  



-- 
Boris Brezillon, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
http://bootlin.com

Re: [PATCH 2/2] mtd: nand: gpmi: add support for specific ECC strength

[Stefan Agner]

On 14.02.2018 20:05, Boris Brezillon wrote:
> On Wed, 14 Feb 2018 16:28:36 +0000
> Han Xu <han.xu@nxp.com> wrote:
> 
>> On 02/06/2018 11:40 AM, Stefan Agner wrote:
>> > Add support for specified ECC strength/size using device tree
>> > properties nand-ecc-strength/nand-ecc-step-size.
>> >
>> > Signed-off-by: Stefan Agner <stefan@agner.ch>
>> > ---
>> >   .../devicetree/bindings/mtd/gpmi-nand.txt          |  5 ++++
>> >   drivers/mtd/nand/gpmi-nand/gpmi-nand.c             | 29 ++++++++++++++--------
>> >   2 files changed, 24 insertions(+), 10 deletions(-)
>> >
>> > diff --git a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
>> > index eb2d9919d063..ea6e9b735160 100644
>> > --- a/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
>> > +++ b/Documentation/devicetree/bindings/mtd/gpmi-nand.txt
>> > @@ -46,6 +46,11 @@ Optional properties:
>> >                          partitions written from Linux with this feature
>> >                          turned on may not be accessible by the BootROM
>> >                          code.
>> > +  - nand-ecc-strength: integer representing the number of bits to correct
>> > +                       per ECC step. Needs to be a multiple of 2.
>> > +  - nand-ecc-step-size: integer representing the number of data bytes
>> > +                       that are covered by a single ECC step. The driver
>> > +                       supports 512 and 1024.
>> >
>> >   The device tree may optionally contain sub-nodes describing partitions of the
>> >   address space. See partition.txt for more detail.
>> > diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>> > index 50f8d4a1b983..8cb378358e11 100644
>> > --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>> > +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
>> > @@ -198,17 +198,15 @@ static inline bool gpmi_check_ecc(struct gpmi_nand_data *this)
>> >    *
>> >    * We may have available oob space in this case.
>> >    */
>> > -static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
>> > +static int set_geometry_by_ecc_info(struct gpmi_nand_data *this,
>> > +			unsigned int ecc_strength, unsigned int ecc_step)
>> >   {
>> >   	struct bch_geometry *geo = &this->bch_geometry;
>> >   	struct nand_chip *chip = &this->nand;
>> >   	struct mtd_info *mtd = nand_to_mtd(chip);
>> >   	unsigned int block_mark_bit_offset;
>> >
>> > -	if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
>> > -		return -EINVAL;
>> > -
>> > -	switch (chip->ecc_step_ds) {
>> > +	switch (ecc_step) {
>> >   	case SZ_512:
>> >   		geo->gf_len = 13;
>> >   		break;
>> > @@ -221,8 +219,8 @@ static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
>> >   			chip->ecc_strength_ds, chip->ecc_step_ds);
>> >   		return -EINVAL;
>> >   	}
>> > -	geo->ecc_chunk_size = chip->ecc_step_ds;
>> > -	geo->ecc_strength = round_up(chip->ecc_strength_ds, 2);
>> > +	geo->ecc_chunk_size = ecc_step;
>> > +	geo->ecc_strength = round_up(ecc_strength, 2);
>> >   	if (!gpmi_check_ecc(this))
>> >   		return -EINVAL;
>> >
>> > @@ -230,7 +228,7 @@ static int set_geometry_by_ecc_info(struct gpmi_nand_data *this)
>> >   	if (geo->ecc_chunk_size < mtd->oobsize) {
>> >   		dev_err(this->dev,
>> >   			"unsupported nand chip. ecc size: %d, oob size : %d\n",
>> > -			chip->ecc_step_ds, mtd->oobsize);
>> > +			ecc_step, mtd->oobsize);
>> >   		return -EINVAL;
>> >   	}
>> >
>> > @@ -423,9 +421,20 @@ static int legacy_set_geometry(struct gpmi_nand_data *this)
>> >
>> >   int common_nfc_set_geometry(struct gpmi_nand_data *this)
>> >   {
>> > +	struct nand_chip *chip = &this->nand;
>> > +
>> > +	if (chip->ecc.strength > 0 && chip->ecc.size > 0)
>> > +		return set_geometry_by_ecc_info(this, chip->ecc.strength,
>> > +						chip->ecc.size);
>> > +
>>
>> I was wondering how to keep, let's say u-boot, and kernel ecc setting
>> aligned, if users can specify the strength and step_ds in DT? Did u-boot
>> enable to get these parameters from DT?
> 
> Both u-boot and Linux have to support using strength/step information
> passed through the DT before you can start patching dts files. Anyway,
> users will have to change their DT (add the nand-ecc-strength/step-size
> properties) to use this feature, so they should quickly notice that
> something is going wrong and update their bootloader or drop those
> nand-ecc-xxx props.
> 

Yes, the MTD stack has support for those properties also in U-Boot.

But currently the GPMI NAND driver (mxs_nand) in U-Boot has no DT
support.

But I do have a preliminary patch set for this. Will send it out soon.

--
Stefan


>> >   	if ((of_property_read_bool(this->dev->of_node, "fsl,use-minimum-ecc"))
>> > -				|| legacy_set_geometry(this))
>> > -		return set_geometry_by_ecc_info(this);
>> > +				|| legacy_set_geometry(this)) {
>> > +		if (!(chip->ecc_strength_ds > 0 && chip->ecc_step_ds > 0))
>> > +			return -EINVAL;
>> > +
>> > +		return set_geometry_by_ecc_info(this, chip->ecc_strength_ds,
>> > +						chip->ecc_step_ds);
>> > +	}
>> >
>> >   	return 0;
>> >   }