On 14.02.2018 20:05, Boris Brezillon wrote:
> 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.
>
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;
>> > }
