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

[Huang Shijie <shijie8@gmail.com>]

On Tue, Oct 14, 2014 at 04:50:27PM +1100, Iwo Mergler wrote:
> 
> >
> > 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).
> 
> Hi Huang,
> 
> 
> just out of interest, have you tried this on the MLC NAND without the patch?
> 
> I'm aware that MLC says you shouldn't write multiple times, but that is
> with a view towards specified data endurance. I would only expect a few
> additional bit errors during the test.
> 
> Did you try the overwrite test?
> 
The following is the test result for overwrite with this MLC patch:

root@imx6qdlsolo:~# insmod mtd_nandbiterrs.ko dev=1 mode=1
[  762.534714] 
[  762.536259] ==================================================
[  762.542115] mtd_nandbiterrs: MTD device: 1
[  762.546326] mtd_nandbiterrs: MTD device size 16777216,
	eraseblock=2097152, page=8192, oob=744
	[  762.554937] mtd_nandbiterrs: Device uses 1 subpages of 8192
	bytes
	[  762.561059] mtd_nandbiterrs: Using page=0, offset=0,
	eraseblock=0
	[  762.571333] mtd_nandbiterrs: overwrite biterrors test
	[  762.576715] mtd_nandbiterrs: write_page
	[  762.590448] mtd_nandbiterrs: error: read failed at 0x0
	[  762.595650] mtd_nandbiterrs: Read reported error -74
	[  762.600625] mtd_nandbiterrs: Bit error histogram (0
			operations total):
	[  762.608586] mtd_nandbiterrs: finished successfully.
	[  762.613501]
	==================================================
	insmod: ERROR: could not insert module mtd_nandbiterrs.ko:
	Input/output error


thanks	   

Huang Shijie