Hi Miquel, Sorry for the constant pestering on this..
On Tue, 23 Mar 2021 at 23:06, Miquel Raynal <miquel.ray...@bootlin.com> wrote: > > # nandbiterrs -i /dev/mtd1 > > incremental biterrors test > > Successfully corrected 0 bit errors per subpage > > Inserted biterror @ 0/5 > > Read reported 4 corrected bit errors > > ECC failure, invalid data despite read success > > This is not a valid behavior. There is something wrong with the way ECC > status is read/retrieved. The read should indeed report 4 corrected bit > errors, but then the data should be valid. Here it means that the > introduced error appears corrected but in fact is not. > We need to understand what status are available and write the > appropriate vendor code. I looked at the datasheet again and the encoding for ecc status seems a bit funky. The chip seems to have only two bits for ECC status with this encoding: 0 - Read success with 0-3 flipped bits. 1 - Read success with 4 flipped bits. 2 - Uncorrectable. 3 - Reserved. This looks almost the same as the Winbond chips with 0 and 1 being successes but with no totally error free status. Anyhow, if 4 bits were corrected is returned for 1 then nandbiterrs reports "ECC failure, invalid data despite read success". If I return 3 bit errors for 0 and -EBADMSG for anything else nandbiterrs doesn't complain anymore but is this right?: # nandbiterrs -i /dev/mtd1 incremental biterrors test Read reported 3 corrected bit errors Successfully corrected 0 bit errors per subpage biterror @ 0/5 Failed to recover 1 bitflips Read error after 1 bit errors per page When running nandbiterrs the status is always 0 before injecting the error and then sometimes 1 and sometimes 2 after the error is injected. Thanks, Daniel
