nand: WARNING: a0000000.nand: the ECC used on your system (1b/256B) is too weak compared to the one required by the NAND chip (4b/512B)

[Christophe Leroy]

Hello Miquel,

I have a board running latest kernel with the following NAND:

[    1.523076] nand: device found, Manufacturer ID: 0x2c, Chip ID: 0xda
[    1.529505] nand: Micron MT29F2G08ABAEAWP
[    1.533526] nand: 256 MiB, SLC, erase size: 128 KiB, page size: 2048, OOB siz
e: 64
[    1.541196] nand: WARNING: a0000000.nand: the ECC used on your system (1b/256
B) is too weak compared to the one required by the NAND chip (4b/512B)

Until now I was using kernel 4.14 and I was having no problem, allthough it was also exhibiting the 
following (less detailed) warning

[    0.591009] nand: WARNING: a0000000.nand: the ECC used on your system is too weak compared to the 
one required by the NAND chip

Now and then I'm using one of the latest kernels (Today is 5.13-rc6), and sometime in one of the 5.x 
releases, I started to get errors like:

[    5.098265] ecc_sw_hamming_correct: uncorrectable ECC error
[    5.103859] ubi0 warning: ubi_io_read: error -74 (ECC error) while reading 60
  bytes from PEB 99:59824, read only 60 bytes, retry
[    5.525843] ecc_sw_hamming_correct: uncorrectable ECC error
[    5.531571] ecc_sw_hamming_correct: uncorrectable ECC error
[    5.537490] ubi0 warning: ubi_io_read: error -74 (ECC error) while reading 30
73 bytes from PEB 107:108976, read only 3073 bytes, retry
[    5.691121] ecc_sw_hamming_correct: uncorrectable ECC error
[    5.696709] ecc_sw_hamming_correct: uncorrectable ECC error
[    5.702426] ecc_sw_hamming_correct: uncorrectable ECC error
[    5.708141] ecc_sw_hamming_correct: uncorrectable ECC error
[    5.714103] ubi0 warning: ubi_io_read: error -74 (ECC error) while reading 30
35 bytes from PEB 107:25144, read only 3035 bytes, retry
[   20.523689] random: crng init done
[   21.892130] ecc_sw_hamming_correct: uncorrectable ECC error
[   21.897730] ubi0 warning: ubi_io_read: error -74 (ECC error) while reading 13
94 bytes from PEB 116:75776, read only 1394 bytes, retry

Most of the time, when the reading of the file fails, I just have to read it once more and it gets 
read without that error.


What am I supposed to do to avoid the ECC weakness warning at startup and to fix that ECC error issue ?

Thanks for your help
Christophe