I think it is because ECC can correct a 1 bit error.  The yaffs_isBlockBad function doesn't bother to do ECC so it is possible that there is a 1 bit error in the block status byte.  Counting the bits < 7 implies that 2 bits are bad & there is no chance that ECC will fix it.

Side note - if what I say is correct, perhaps the tags should be ECC fixed (if bits < 8) & then checked against 0xFF, otherwise it would be possible for the block status byte to have a single bit error, but also other bytes of the tag to have errors - which would also invalidate the ECC check?

Ie, 
	if (countBits < 7)
		return 1;
	else
	if (countBits != 0xFF)
	{
	  ecc_correct_tags
 	  if (corrected_status != 0xFF)
	}

Cheers
Brad

> -----Original Message-----
> From: Jim Muchow [mailto:james.muchow@qlogic.com] 
> Sent: Wednesday, 11 June 2003 4:20 a.m.
> To: yaffs@toby-churchill.org
> Subject: Block Status Question
> 
> 
> In yaffs_IsBlockBad() a test is made for the number of bits
> in each byte. The original test for 0xFF is #if'd out.
> 
> The test for failure is less than 7. Shouldn't this be 8?
> What am I missing?
> 
> JM
> 
> 
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