On Wed, 14 Feb 2018 16:28:36 +0000
Han Xu <han...@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 <ste...@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
