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Date: Mon, 28 Oct 2013 10:57:33 +0800
From: Huang Shijie <b32955@freescale.com>
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Subject: Re: [PATCH] ubi: attach: do not return -EINVAL if the
 mtd->numeraseregions is 1
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=E4=BA=8E 2013=E5=B9=B410=E6=9C=8826=E6=97=A5 17:47, Artem Bityutskiy =E5=
=86=99=E9=81=93:
> What is 'numeraseregions =3D=3D 1'? How is it different to 'numerasereg=
ions
> =3D=3D 0'?
>
> Is the "main" area covered by mtd->size, or 'mtd->size' spans the entir=
e
> chip and includes all the regions?
>
i think the mtd->size spans the entire chip and include the all the regio=
ns.


> What is the flash you are dealing with? Surely this is not gpmi-nand?
I meet this bug with a Micron's Parallel Nor: M29W256GL
it is not used by the gpmi-nand, it's used by weim driver:=20
drivers/bus/imx-weim.c

this NOR's Number of erase block regions is 1, i quote the test here,=20
see page 50
(i will send you the datasheet in a private email):

"
   It specifes the number of regions containning contiguous erase blocks=20
of the same size.

"

please see allocate_partition():

  =20
-------------------------------------------------------------------------=
--------
   if (master->numeraseregions > 1) {
       ................
   } else {
       /* Single erase size */
   }

  =20
-------------------------------------------------------------------------=
--------

this NOR is 32MB, its master partion has 1 for "numeraseregions". if we=20
add a 32MB slave partition
  to this NOR, the slave partition does NOT inherit the numeraseregions=20
of the master partition.
So the ubiattach will succeed with the slave partition.

But if we attach the master partition directly, we will fails.

thanks
Huang Shijie