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

[Han Xu]

On Thu, Mar 17, 2022 at 8:27 AM Frieder Schrempf <
frieder.schrempf at kontron.de> wrote:

> Hi Stefano,
>
> this old patch was delegated to you in patchwork. If you're not the
> correct maintainer to address, please let me know. As the NAND layer
> seems to be unmaintained at the moment, I'm not sure whom to ask.
>
> This patch fixes a regression that was introduced by 616f03dabacb ("
> mtd: gpmi: change the BCH layout setting for large oob NAND") which
> alters the BCH layout in a way that doesn't match with the
> implementation in the Linux kernel.
>
> This causes failures when loading an UBI image in U-Boot that was
> flashed by Linux or vice versa (see [1]).
>
> There has been an approach to fix this through an optional devicetree
> property in 51cdf83eea ("mtd: gpmi: provide the option to use legacy bch
> geometry"), but this is not acceptable. The "legacy" BCH layout
> compatible with Linux should be used by default.
>
> The approach to upstream the "new" layout to the kernel [2] seems to be
> stalled and even if it would succeed, it would break systems that use an
> old U-Boot and a new kernel, which is again not really acceptable in my
> opinion.


Hi Frieder,

I am not in office this week. I will send another patch set to change in
both kernel and u-boot to fix the compatible issue.


>
> For the reasons above I would like to ask U-Boot maintainers to pick up
> this patch.
>
> Thanks
> Frieder
>
> [1] https://lists.denx.de/pipermail/u-boot/2022-March/477828.html
> [2]
>
> https://patchwork.ozlabs.org/project/linux-mtd/patch/20210522205136.19465-2-han.xu@nxp.com/
>
> Am 20.05.21 um 11:09 schrieb Sean Nyekjaer:
> > On 13/05/2021 22.02, han.xu wrote:
> >> 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.
> >>
> > Any progress on this?
> >
> > I see your patch in:
> >
> https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsource.codeaurora.org%2Fexternal%2Fimx%2Flinux-imx%2Fcommit%2Fdrivers%2Fmtd%2Fnand%2Fraw%2Fgpmi-nand%3Fh%3Dimx_5.4.70_2.3.0%26id%3Dae980dccc6189956fab047958ad0a70ec4951439&data=04%7C01%7Cfrieder.schrempf%40kontron.de%7C275b7f11361e4fd3eb7e08d91b6f0e45%7C8c9d3c973fd941c8a2b1646f3942daf1%7C0%7C0%7C637570986066857865%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=L4xAN9HDl68dmA%2FX6nnP%2Buqh6CUKTQZJeFWja5EvmPI%3D&reserved=0
> >
> > But I can't find the option for selecting legacy mode in the
> devicetree...
> >
> > /Sean
>
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>
-- 
Sincerely,

Han XU