[EXT] [PATCH] mtd: mxs_nand: default to legacy bch and rename to modern bch option

[han.xu]

On 21/05/11 07:08AM, Sean Nyekjaer wrote:
> Caution: EXT Email
> 
> On 11/05/2021 04.49, han.xu wrote:
> > On 21/05/10 12:00PM, Sean Nyekjaer wrote:
> >> Caution: EXT Email
> >>
> >> Linux kernel defaults to use legacy bch setting, this was creating a
> >> mismatch between U-boot and Linux default settings.
> > Kernel uses the NAND chip specified minimum ecc strength and steps by default
> > not the legacy bch setting, unless users enable it in DT file.
> >
> 
> Hi,
> 
> Adding, mtd-list and Miquel
> 
> With u-boot dtb:
> &gpmi {
>         pinctrl-names = "default";
>         pinctrl-0 = <&pinctrl_gpmi_nand1>;
>         compatible = "fsl,imx7d-gpmi-nand";
>         nand-on-flash-bbt;
>         status = "okay";
> };
> 
> With linux dtb (mainline 5.10):
> &gpmi {
>         pinctrl-names = "default";
>         pinctrl-0 = <&pinctrl_gpmi_nand1>;
>         nand-on-flash-bbt;
>         status = "okay";
> };
> 
> U-boot prior to commit 51cdf83eea selected 18 bit ECC, after that commit it selects 8 bits.
> With legacy option it selects 18.
> Linux is selecting 18 bits ;) So now we have a mismatch.
> 
> I have been searching for the legacy option in the mainline kernel can't find it ;)
> Please show me where it is (is it in the NXP fork?)

You are right, it's only fixed in NXP fork, with kernel driver modification. We
prefer the current u-boot bch geometry, so I will send out a kernel patch to
make them align.

> 
> /Sean