Re: [BUG] pxa3xx: wait time out when scanning for bb

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Sun, 17 Dec 2017 12:56:01 +0100
Sean Nyekjaer <sean.nyekjaer@prevas.dk> wrote:

> Hi Miquel
> >>> I am very sorry for the delay but it took me some time to figure a
> >>> way to reproduce your situation until I started doing the exact
> >>> sequence I asked you to follow. It turns out there was a nasty error
> >>> in the parser so you could not observe the last blocks of your chip
> >>> because I messed up with high addresses.  
> >> Fantastic always nice to be able to reproduce the issue. Glad to be
> >> able to help :-)
> >>  
> >>> I updated the Github branch [1], can you rebase on top of it? I think
> >>> this time we should get something :)  
> >> I just did a quick boot with the new commits, and the kernel is able
> >> to find the bbt table :-)  
> > Good ! :-)
> >
> > So with nand-ecc-mode = "none" + on-flash-bbt, there is no more issue,
> > right?  
> No more issue with reading the bbt :-)
> >  
> >> I also tried booting with ECC enabled and with that enabled the
> >> driver is unable to read the bbt and marked all blocks bad.  
> > And if I understand correctly, if you remove nand-ecc-mode = "none" (or
> > set it to "hw"), the kernel fails to find the BBT, that is right?  
> Yes.
> >
> > As I was not expecting such a quick answer, I did push another patch
> > after sending my email that fixes an issue in mtdcore.c, please check
> > you have it (there are a few "fixup!" patches, and on top of them you
> > must find one which is a well-formatted patch about
> > mtd_check_oob_ops()).  
> I have rebased on top of 9aee88a618f8 mtd: Fix mtd_check_oob_ops()
> >
> > I learned that today: to get a prompt while all blocks are bad, you can
> > add:
> >
> >      chip->options |= NAND_SKIP_BBTSCAN;
> >
> > Before nand_scan_tail().
> >
> > If you can reach a prompt with the failing configuration and when you
> > will have the time, I will welcome a dump of the same area as before
> > so we will try to understand what is wrong now ! :)  
> Nice one, a lot easier to read whats happens
> 
> nanddump of BBT without ECC enabled:
> https://gist.github.com/anonymous/627e5be058ed93c106d61641f6aa5da0
> 
> nanddump of BBT with ECC enabled:
> https://gist.github.com/anonymous/76b3240f156c6547cf76d59f2aae49fe

Another test that is worth doing: try to dump with ECC enabled:

# nanddump -op -l 0x800 --bb=dumpbad -s 0xYYYYYYY /dev/mtd1

> bootsnippet with ECC and NAND_SKIP_BBTSCAN enabled.
> https://gist.github.com/anonymous/0d9be95cd9c36ff006f7aa03e7c2cc85
> 
> Please let me know what traces you need to fix the ECC :-)
> 
> /Sean