On 26.01.2023 02:14, William Zhang wrote:
On 01/21/2023 03:43 PM, Linus Walleij wrote:
For BRCMNAND with 1-bit BCH ECC (BCH-1) such as used on the
D-Link DIR-885L and DIR-890L routers, we need to explicitly
select the ECC like this in the device tree:
nand-ecc-algo = "bch";
nand-ecc-strength = <1>;
nand-ecc-step-size = <512>;
This is handled by the Linux kernel but U-Boot core does
not respect this. Fix it up by parsing the algorithm and
preserve the behaviour using this property to select
software BCH as far as possible.
For 1 bit HW ECC, the BRCMNAND driver only uses HAMMING ECC. The
brcmnand_setup_dev function should take care of it with just these two
properties in the device tress without any code changes:
nand-ecc-strength = <1>;
nand-ecc-step-size = <512>;
unless these D-Link device has always been using software BCH-1 and wants to
continue to use software BCH-1.
Please check
arch/arm/boot/dts/bcm5301x-nand-cs0-bch1.dtsi
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/bcm5301x-nand-cs0-bch1.dtsi
It's included by
arch/arm/boot/dts/bcm47094-dlink-dir-885l.dts
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/bcm47094-dlink-dir-885l.dts
I can confirm D-Link decided to use BCH-1 for some of its devices. I
didn't expect it neither and that required fixing up brcmnand driver in
Linux actually.
BTW, I didn't see this change from master branch of linux nand base driver. The
"nand-ecc-algo" is only used by the ecc engine code(ecc.c) but this code is not
in the u-boot obviously. Were you porting this from a different version of linux nand
driver?
My original proposal for brcmnand looked like this:
[PATCH 3/3] mtd: brcmnand: respect ECC algorithm set by NAND subsystem
https://lore.kernel.org/lkml/1461324197-1333-3-git-send-email-zaj...@gmail.com/
It was reworked by Brian to a more backward compatible solution that got
accepted:
[PATCH] mtd: brcmnand: respect ECC algorithm set by the NAND subsystem
https://lore.kernel.org/lkml/20160426055355.GA25981@localhost/
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=666b65683dad9aa90efaa4aad24ef3710101e3aa
