Re: [PATCH v3 0/3] mtd: nand: gpmi: add proper raw access support

[Boris Brezillon]

On Wed, 8 Oct 2014 22:24:40 +0800
Huang Shijie <shijie8@xxxxxxxxx> wrote:

> On Tue, Sep 23, 2014 at 04:07:33PM +0200, Boris BREZILLON wrote:
> > Hello Huang, Brian,
> > 
> > This is just a new proposal to support raw accesses in a more standard way
> > in the GPMI driver.
> > This series has been tested on an imx28 board.
> > 
> > Any suggestions are welcome.
> > 
> > Best Regards,
> > 
> > Boris
> > 
> > Changes since v2:
> >  - fixed a bug in gpmi_move_bits
> >  - add a raw_buffer field to be used when using raw access methods
> >    (experienced memory corruptions when directly using page_buffer_virt
> >    buffer)
> >  - add raw OOB access functions
> 
> I tested this patch set today with the imx6dl-sabreauto board.
> 
>     NAND: Micron MT29F64G08CBABAWP
> 	8192MiB, MLC, page size: 8192, OOB size: 744
> 
>     ECC: 40bit
> 
> The result:
> 
> [ 3672.779009] ==================================================
> [ 3672.784974] mtd_nandbiterrs: MTD device: 0
> [ 3672.789480] mtd_nandbiterrs: MTD device size 16777216, eraseblock=2097152, page=8192, oob=744
> [ 3672.798169] mtd_nandbiterrs: Device uses 1 subpages of 8192 bytes
> [ 3672.804554] mtd_nandbiterrs: Using page=0, offset=0, eraseblock=0
> [ 3672.812497] mtd_nandbiterrs: incremental biterrors test
> [ 3672.818688] mtd_nandbiterrs: write_page
> [ 3672.825529] mtd_nandbiterrs: rewrite page
> [ 3672.837290] mtd_nandbiterrs: read_page
> [ 3672.848407] mtd_nandbiterrs: error: read failed at 0x0
> [ 3672.853644] mtd_nandbiterrs: After 0 biterrors per subpage, read reported error -74
> [ 3672.862932] mtd_nandbiterrs: finished successfully.
> [ 3672.867837] ==================================================
> 
> [ 3745.282368] ==================================================
> [ 3745.288227] mtd_nandbiterrs: MTD device: 0
> [ 3745.292913] mtd_nandbiterrs: MTD device size 16777216, eraseblock=2097152, page=8192, oob=744
> [ 3745.301897] mtd_nandbiterrs: Device uses 1 subpages of 8192 bytes
> [ 3745.308023] mtd_nandbiterrs: Using page=1, offset=8192, eraseblock=0
> [ 3745.316778] mtd_nandbiterrs: incremental biterrors test
> [ 3745.323017] mtd_nandbiterrs: write_page
> [ 3745.328616] mtd_nandbiterrs: rewrite page
> [ 3745.334191] mtd_nandbiterrs: read_page
> [ 3745.346878] mtd_nandbiterrs: error: read failed at 0x2000
> [ 3745.352352] mtd_nandbiterrs: After 0 biterrors per subpage, read reported error -74
> [ 3745.361281] mtd_nandbiterrs: finished successfully.
> [ 3745.366173] ==================================================
> 
> 
> Is this okay?

No, it doesn't seem to be correct.
But it's an MLC flash, so you'll most probably need to apply this patch
to nandbiterrs testsuite:

http://code.bulix.org/f69wuu-87021

This patch is flashing the block between each bitflip insertion to
avoid multiple write without erasure (which, AFAIK, is not supported
by MLC flashes).

Can you also try to write zeros to a NAND page and then dump it in
raw mode (and provide me with the resulted /tmp/dump file or an
hexdump output of this file) ?

flash_erase /dev/mtdX 0 1
dd if=/dev/zero of=/tmp/zero bs=8k count=1
nandwrite /dev/mtdX /tmp/zero
nanddump -n -o -l 8192 -f /tmp/dump /dev/mtdX 

Thanks,

Boris

-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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