Re: [PATCH v4 1/2] mtd: mediatek: device tree docs for MTK Smart Device Gen1 NAND

Boris Brezillon
2016-05-10T12:22:46Z

On Tue, 10 May 2016 07:57:25 -0400
Jorge Ramirez <jorge.ramirez-ortiz@linaro.org> wrote:

> On 05/06/2016 09:38 AM, Boris Brezillon wrote:
> > Hi Jorge,
> >
> > On Fri, 29 Apr 2016 12:17:21 -0400
> > Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org> wrote:
> >
> >> This patch adds documentation support for Smart Device Gen1 type of
> >> NAND controllers.
> >>
> >> Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
> >> ---
> >> Documentation/devicetree/bindings/mtd/mtk-nand.txt | 161 +++++++++++++++++++++
> >> 1 file changed, 161 insertions(+)
> >> create mode 100644 Documentation/devicetree/bindings/mtd/mtk-nand.txt
> >>
> >> diff --git a/Documentation/devicetree/bindings/mtd/mtk-nand.txt b/Documentation/devicetree/bindings/mtd/mtk-nand.txt
> >> new file mode 100644
> >> index 0000000..175767d
> >> --- /dev/null
> >> +++ b/Documentation/devicetree/bindings/mtd/mtk-nand.txt
> > [...]
> >
> >> +
> >> +Children nodes properties:
> >> +- reg: Chip Select Signal, default 0.
> >> + Set as reg = <0>, <1> when need 2 CS.
> >> +Optional:
> >> +- nand-on-flash-bbt: Store BBT on NAND Flash.
> >> +- nand-ecc-mode: the NAND ecc mode (check driver for supported modes)
> >> +- nand-ecc-step-size: Number of data bytes covered by a single ECC step.
> >> + The controller only supports 512 and 1024.
> >> + For large page NANDs ther recommended value is 1024.
> >> +- nand-ecc-strength: Number of bits to correct per ECC step.
> >> + The valid values that the controller supports are: 4, 6,
> >> + 8, 10, 12, 14, 16, 18, 20, 22, 24, 28, 32, 36, 40, 44,
> >> + 48, 52, 56, 60.
> >> + The strength should be calculated as follows:
> >> + E = (S - F) * 8 / 14
> >> + S = O / (P / Q)
> >> + E :nand-ecc-strength;
> >> + S :spare size per sector;
> >> + F : FDM size, should be in the range [1,8].
> >> + It is used to store free oob data.
> >> + O : oob size;
> >> + P : page size;
> >> + Q :nand-ecc-step-size
> >> + If the result does not match any one of the listed
> >> + choices above, please select the smaller valid value from
> >> + the list.
> >> + (otherwise the driver will do the clamping at runtime).
> >> +- vmch-supply: NAND power supply.
> > Where is this supply name coming from? I most datasheets I see Vdd or
> > Vcc, but nothing close to Vmch.
> >
> >
> >
>
> um yes we are removing this since we dont use it (it is the NAND vcc on
> some other MTK platform to do power management via regulator).
>

Ok, no problem. Actually it's yet another property that should be
described in the generic binding doc.

--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering