[U-Boot] PATCH: bugfix for nand erase failure with bad blocks

[Michele De Candia (VT) <michele.decandia@valueteam.com>]

Scott Wood wrote:
> Wolfgang Denk wrote:
>> Dear "Michele De Candia (VT)",
>>
>> In message <4A37F7BF.2090101@valueteam.com> you wrote:
>>>>> this patch fixes a bug for 'nand erase' command: when bad blocks 
>>>>> are present into erasing area, they were skipped but the erased 
>>>>> size was updated anyway.
>>>> And what exactly is the bug in this behaviour?
>>>>   
>>> I think that 'erase' should have the same behaviour of 'write' and 
>>> 'read' commands: skip bad blocks until read/write size is reached. 
>>> If you write a script that erases and then writes a NAND area and 
>>> bad blocks are not skipped while erasing (as U-Boot actually does), 
>>> the following 'write'  is successfully done but ECC checks fail on 
>>> next read on the same area.
>>
>> I see - thanks for the explanation.
>>
>> Hm... actually I think the write should fail in such a case...
>>
>> Scott, what do you think?
>
> I think the current behavior is reasonable.  You're erasing a specific 
> region of flash, not an amount needed to hold a certain amount of data.
>
 From this point of view you're in the right; maybe this would be 
explained in 'README.nand' documentation or what do you think about add 
ing an option to 'nand erase' command to consider 'size' field as the 
effective blocks size to be erased and not as the area size?
> While I can see the appeal of Michele's suggestion, I think it would 
> be more error-prone as people trying to erase a region rather than 
> just the size of data could erase too much.
>
> It definitely should not be an error to erase a region that happens to 
> contain a bad block.  Bad blocks are expected and we need to work 
> around them.
>
> -Scott


-- 

*Michele Jr **De Candia*

------------------------------------------------------------------------

Value Team

Via Vespri Siciliani, 9
20146 Milano
Tel. +39 0248985722
michele.decandia at valueteam.com <mailto:michele.decandia@valueteam.com>
http://www.valueteam.com

 

CONFIDENTIALITY NOTICE -This message and its attachments (if any) may 
contain confidential, proprietary or legally privileged information and 
is intended only for the use of the addressee named above. No 
confidentiality or privilege is waived or lost by any mistransmission. 
If you are not the intended recipient of this message you are hereby 
notified that you must not use, disseminate, copy it in any form or take 
any action in reliance on it. If you have received this message in error 
please delete it and any copies of it and kindly inform the sender of 
this e-mail by replying or go to www.valueteam.com 
<http://www.valueteam.com> on 'contacts'.