[U-Boot] Bad block present before NAND flash partition offset

[Madhu koriginja]

Hi All,
Any suggestions on the above issue?
Thanks


On Fri, Jan 18, 2019 at 6:20 PM Madhu koriginja <madhava.koriginja at gmail.com>
wrote:

> Hi All,
> In my NAND flash one bad block present before some 'X' binary offset,
> after this binary partition kernel and rootfs partitions are present.
> In U-Boot when I access this x binary using the offset address it is not
> getting binary file content, because of one bad block the 'X' binary
> flashed in next block after the offset. I used nand_read and
> nand_read_skip_bad functions, nand_read_skip_bad function is handling if
> bad block present between offset and the length of the data required after
> offset.
>
> I want to know is there any function in existing u-boot source code to
> handle  the above issue(if bad blocks present before offset)?
>
> If there is no provision, there are two ways to solve it
> 1. it is working if I change the offset value of 'X' binary in U-boot
> source code based on the no. of bad blocks present before offset 'X'
> binary.
> 2. Check the no. of bad blocks present before offset at run time and add
> those many bad blocks length to the offset.
> First method does not work if different boards NAND flash have bad blocks
> in different places, but second method handles this.
>
> With the second method, the changes in my specific code to access my 'X'
> binary, it does not affect common code.
> After this U-boot is failing to load kernel, because the same issue for
> kernel also, U-boot is reading the kernel image from the kernel offset, but
> the kernel image also flashed after 1 block due to 1 bad block.
> If I follow the above second method here also, I need to do change in
> "nand read" command function. But with this change it may create some
> confusion to others in situation like, if some one debugging and wants to
> read the content from some offset, if bad block present before this offset,
> it does not read exactly from that offset, it reads after that due to bad
> block because nand read function is modified above.
> I want to address this issue in general way, to solve the problem in
> dynamic way to handle different bad blocks can present in different boards
> and do not create confusion. Please comment.
>
> I am thinking in nand read function while displaying the content it should
> print from which address it is displaying, so that if they observe it they
> know it is displaying after the specified offset due to bad blocks, but
> people may miss to see the address print.
>
> Thanks.
>