Re: mtd_oobtest fails with GPMI-NAND

[Vikram Narayanan <vikram186@gmail.com>]

Hello Stefan,

On 5/10/2013 11:50 AM, Stefan Roese wrote:
> Hi Vikram,
>
> On 05/09/2013 02:30 PM, Vikram Narayanan wrote:
>>> I might be seeing something similar on my iMX6 board. Here
>>> mtd_subpagetest sometimes fails.
>>
>> AFAIR, subpagetest passed for me when I tested.
>>
>> BTW, What kind of errors are you getting? Any logs?
>
> Sure. Here 2 logs with v3.9.1:
>
> # insmod mtd_subpagetest.ko dev=3
> [  315.947734] mtd_subpagetest: verified up to eraseblock 0
> [  317.140658] mtd_subpagetest: error: read failed at 0xd60800

> [ 2561.996470] mtd_subpagetest: error: read failed at 0xe380800

Looks like it is happening at random. Two different physical locations 
on two different runs.

>>>
>>> What is the current status on your platform? Did you resolve this
>>> problem? If yes, what did you have to change/fix?
>>
>> Unfortunately no. I haven't got enough time to look into this.
>
> Too bad. Could you please explain again, how you first noticed
> that the you might have a problem with NAND on your imx6 board?

For me, the error (-74) happened when the kernel is finally trying to 
mount the rootfs. It is random as well.

<http://www.linux-mtd.infradead.org/faq/ubi.html#L_ecc_error>
As suggested in the above link, I tried to run the oobtest and it was 
failing due to the missing ecc_layout structure. That's how this thread 
was born.

> We noticed a problem first in U-Boot by using the following
> commands:
>
> => nand erase.part ubi; ubi part ubi
>
> This works the first time without any problem. But the 2nd time
> it leads to "uncorrectable errors" (0xfe) while reading from some
> blocks. And those failing blocks tend to be the same (more or less).

> Perhaps you might want to test this in U-Boot (if you use it)
> as well.

I'm using u-boot v2012.10, with no extra patches for mtd/ubi layers.

I tried in both the ways. Issued "nand erase; ubi part" and "ubi part" 
alone. For me, It didn't give any "uncorrectable errors" error you've 
mentioned.

The only error I came across in u-boot is "fixable bit-flip" issue. My 
colleagues have reported it sometime back. But I couldn't reproduce it 
and neither could they.

Can you please post the logs for the "uncorrectable errors" in u-boot?
That might give some hints to Huang.

Thanks,
Vikram