MT7621 NAND OOB misdetect

[Peter Naulls]

On 2/11/23 08:10, Chuanhong Guo wrote:
> Hi!
> 

>>
>> # nanddump -a /dev/mtd2
>> ECC failed: 8
>> ECC corrected: 0
>> Number of bad blocks: 0
>> Number of bbt blocks: 0
>> Block size 131072, page size 2048, OOB size 128
>> Dumping data starting at 0x00000000 and ending at 0x00040000...
>> libmtd: error!: MEMGETBADBLOCK ioctl failed for eraseblock 0 (mtd2)
>>           error 77 (Bad message)
>> nanddump: error!: libmtd: mtd_is_bad
>>
>> I haven't been able to find anything on what this error means in practice.
> 
> You could try printing the spare size and ecc strength used in the
> old driver, replacing the calculation in the new driver with
> hard-coded values and see if that works. If it works, you can
> implement the ecc strength override in our driver.
> 

Thanks. I'm not real familiar with this, so it's slow going.  I'm sure the 
answer is simple.  Here's some more info from u-boot:

# MTK NAND # : Use HW ECC
NAND ID [C2 F1 80 91 03]
Device found in MTK table, ID: c2f1, EXT_ID: 809103
Support this Device in MTK table! c2f1
select_chip
[NAND]select ecc bit:12, sparesize :112 spare_per_sector=28
Signature matched and data read!
load_fact_bbt success 1023
load fact bbt success
[mtk_nand] probe successfully!
mtd->writesize=2048 mtd->oobsize=112,   mtd->erasesize=131072  devinfo.iowidth=8


 From the vendor mtk_nand2 driver:

	nand_chip->ecc.mode = hw->nand_ecc_mode;    /* enable ECC */
	nand_chip->ecc.strength = 1;


[    9.398860] [NAND]select ecc bit:12, sparesize :112 spare_per_sector=28

Also note:

	mtd->oobsize = devinfo.sparesize;

Which might be the misreporting.


In our driver, it comes out as:

[   16.091826] nand: 128 MiB, SLC, erase size: 128 KiB, page size: 2048, OOB 
size: 128
[   16.107083] mt7621-nand 1e003000.nand: ECC strength adjusted to 12 bits

I tried adjusting in nand_onfi.c ecc_bits = 12 and spare_bytes_per_page to 112, 
to no avail.

I set that back, and then in mt7621_nfc_calc_ecc_strength tried setting the
strength to 1, with no obvious difference.

What to try next, thanks!