[Q] What is struct mtd_partition.ecclayout & who uses it?

[Q] What is struct mtd_partition.ecclayout & who uses it?

[Brian Foster]

  In `struct mtd_partition' there is an undocumented field
  `.ecclayout' which (modulo a name/type change) has existed since
  Linus's original GIT commit 1da177e4c3f4 ("Linux-2.6.12-rc2").

  However, with one trivial exception, I can_NOT_ find any users
  of this field.  The exception is it is initialized to NULL in
  mtd_add_partition().

  Indeed, a trial build (of v3.10 for my system) with that field
  and its one known usage /*commented-out*/ succeeded, proving
  that *IF* it is used at all, it's probably by some specific
  NAND(-controller?) driver(s?).

  Any idea which one(s?)?

  Offhand, this looks like a long-dead something, with the only
  clew being the comment (in <linux/mtd/partitions.h>):

     /* out of band layout for this partition (NAND only) */

cheers!
	-blf-

-- 
Brian Foster
Principal MTS, Software        |  La Ciotat, France
Maxim Integrated               |  http://www.maximintegrated.com/

Re: [Q] What is struct mtd_partition.ecclayout & who uses it?

[Brian Norris]

On Wed, Oct 7, 2015 at 2:11 PM, Brian Foster
<brian.foster@maximintegrated.com> wrote:
>
>   In `struct mtd_partition' there is an undocumented field
>   `.ecclayout' which (modulo a name/type change) has existed since
>   Linus's original GIT commit 1da177e4c3f4 ("Linux-2.6.12-rc2").
>
>   However, with one trivial exception, I can_NOT_ find any users
>   of this field.  The exception is it is initialized to NULL in
>   mtd_add_partition().
>
>   Indeed, a trial build (of v3.10 for my system) with that field
>   and its one known usage /*commented-out*/ succeeded, proving
>   that *IF* it is used at all, it's probably by some specific
>   NAND(-controller?) driver(s?).
>
>   Any idea which one(s?)?
>
>   Offhand, this looks like a long-dead something, with the only
>   clew being the comment (in <linux/mtd/partitions.h>):
>
>      /* out of band layout for this partition (NAND only) */

Looks like you've found a dead field. Not too surprising.

If it's not used in mainline, it's ripe for killing. Patches welcome!

Regards,
Brian