Re: [PATCH v2 6/6] mtd: rawnand: sunxi: introduce variable user data length

From: Richard GENOUD

Date: Fri Mar 13 2026 - 09:20:59 EST

Le 12/03/2026 à 15:41, Miquel Raynal a écrit :
Hello Richard,

On 05/03/2026 at 11:01:37 +01, Richard Genoud <richard.genoud@xxxxxxxxxxx> wrote:

In Allwinner SoCs, user data can be added in OOB before each ECC data.
For older SoCs like A10, the user data size was the size of a register
(4 bytes) and was mandatory before each ECC step.
So, the A10 OOB Layout is:
[4Bytes USER_DATA_STEP0] [ECC_STEP0 bytes]
[4bytes USER_DATA_STEP1] [ECC_STEP1 bytes]
...
NB: the BBM is stored at the beginning of the USER_DATA_STEP0.

Now, for H6/H616 NAND flash controller, this user data can have a
different size for each step.
And the vendor has chosen a different layout from the one on A10, using
8 bytes for step 0 and nothing for further steps:
[8bytes USER_DATA_STEP0] [ECC_STEP0 bytes] [ECC_STEP1 bytes]...
(Still with BBM stored at the beginning of the USER_DATA_STEP0)

I would rather be in favour of not following $(random vendor) firmware
layout. Upstream, it makes probably more sense to just allow access to
the maximum number of bytes that can be covered by the ECC engine, so I
would rather be in favour of computing the maximum size that you can set
for each step, without going over the OOB size.
Ok, I'll write an implementation for that.

Thanks !


Once this set up, I believe adapting the driver locally (out of tree) to
match a specific vendor layout would be rather straightforward, as all
the configuration pieces would already be in place.

Thanks,
Miquèl