Hi, Mike

On 11/28/2012 3:35 AM, Mike Dunn wrote:

On 11/27/2012 10:59 AM, Mike Dunn wrote:

quoted

On 11/27/2012 02:50 AM, Josh Wu wrote:

quoted

This patch fix pmecc's read_page() to return maximum number of bitflips, 0 if uncorrectable.

In the commit: 3f91e94f7f511de74c0d2abe08672ccdbdd1961c ("mtd: nand: read_page() returns max_bitflips ()"),
The ecc.read_page() is changed to return the maximum number of bitflips.
And when meet uncorrectable bitflips it needs to return 0.

See the comment in nand.h:
  * @read_page:	function to read a page according to the ECC generator
  *		requirements; returns maximum number of bitflips corrected in
  *		any single ECC step, 0 if bitflips uncorrectable, -EIO hw error

Signed-off-by: Josh Wu <redacted>
---
change since v1:
   1. add detail commit message for the fix.
   2. return 0 when meet uncorrectable bitflips according to Mike Dunn's suggestion.

Reviewed-by: Mike Dunn <redacted>

I see now the pmecc controller patch in the git log.  Nice work.

BTW, with such a wide range for ecc strength - up to 24 bits, according to the
commit message for the pmecc patch - you may want to think about setting an
appropriate bitflip_threshold in the driver.  I'm not a nand expert, and I don't
know much about the atmel_nand specifically, but I would think that if 23 bits
are corrected on a page of size 2k (or less), maybe a return code of -EUCLEAN
from mtd_read() might be appropriate.

After checking the nand_base.c, I saw it will set the 
mtd.bitflip_threshold to mtd->ecc.strength during nand_scan_tail().
in the atmel_nand code, the ecc strength will be set correctly, that 
means bitflip_threashold should be set up correctly by default.
so I think I don't need set up the the bitflip_threshold anymore if I 
set ecc strength correctly. Am I missing any point here?

Thanks,
Josh Wu

Mike