Re: Current mainline (3.6-rc3) UBIFS errors

[David Jander <david.jander@protonic.nl>]

On Thu, 23 Aug 2012 13:18:37 +0300
Artem Bityutskiy <dedekind1@gmail.com> wrote:

> On Thu, 2012-08-23 at 11:27 +0200, David Jander wrote:
> > On Thu, 23 Aug 2012 11:47:53 +0300
> > Artem Bityutskiy <dedekind1@gmail.com> wrote:
> > 
> > > On Thu, 2012-08-23 at 10:39 +0200, David Jander wrote:
> > > > On Thu, 23 Aug 2012 11:10:08 +0300
> > > > Artem Bityutskiy <dedekind1@gmail.com> wrote:
> > > > 
> > > > > On Thu, 2012-08-23 at 09:50 +0200, David Jander wrote:
> > > > > > [    4.069409] UBI warning: ubi_io_read: error -74 (ECC error) while
> > > > > > reading 160 bytes from PEB 5616:87112, read only 160 bytes
> > > > > 
> > > > > Hi, looks like a problem with your driver. For some reasons it returns
> > > > > ECC errors when reading small amount of data (160 bytes). Did you run
> > > > > mtd tests - to they pass?
> > > > 
> > > > I thought so at first, but this error appeared on two different hardware
> > > > platforms at the same time, when upgrading to latest mainline. I am coming
> > > > from kernel 3.1, which worked fine on the MPC5121e. The ARM platform also
> > > > worked without problems on a previous version (I think it was 3.4-something,
> > > > not so sure right now). The only common piece of hardware/driver is the actual
> > > > NAND flash chip on both boards (Samsung K9K8G08... SLC 8Gbit NAND), so I
> > > > thought this had to be a (temporary) issue in current mainline code.
> > > 
> > > A change in the mtd layer probably caused this.
> > > 
> > > > > So UBI just tells that it cannot read, the root-cause is in the driver.
> > > > 
> > > > Two different drivers... same issue!?
> > > 
> > > Quite possible if there is a bug in mtd layer. First try to find out the
> > > latest working kernel release.
> > 
> > Ok, sounds reasonable.
> > I found kernel 3.5 works fine. Now bisecting...
> 
> If you want to check whether it is UBI/UBIFS to blame, please, pull the
> ubifs-v3.5.git back-port tree and test. The back-port tree contains all
> UBI/UBIFS changes which we have done after 3.5.

All of a sudden I am finding myself unable to reproduce the problem. Baffled
and confused, my only two explanations for this is that either somehow while
switching kernel versions the .config file got altered in such a way that
CONFIG_MTD_NAND_ECC_SMC magically changed value or that some cosmic
radiation corrupted _both_ NAND chips at the same time :-(
My apologies for wasting your time.
I'll report back if I ever happen to reproduce this issue.... it might still
be there but just hard to trigger... who knows.

Best regards,

-- 
David Jander