From mboxrd@z Thu Jan  1 00:00:00 1970
From: Arnd Bergmann <arnd@arndb.de>
To: Roger Quadros <rogerq@ti.com>
Subject: Re: [PATCH] nand: omap2: fix building with CONFIG_MTD_NAND_OMAP_BCH=m
Date: Wed, 01 Oct 2014 12:13:16 +0200
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Cc: pekon <pekon@pek-sem.com>, linux-mtd@lists.infradead.org,
 Ezequiel Garcia <ezequiel.garcia@free-electrons.com>,
 Brian Norris <computersforpeace@gmail.com>,
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On Wednesday 01 October 2014 13:07:51 Roger Quadros wrote:
> On 10/01/2014 12:56 PM, Arnd Bergmann wrote:
> > On Wednesday 01 October 2014 12:32:09 Roger Quadros wrote:
> >>
> >> With this patch NAND probe on DRA7xx fails like so
> >>
> >> [    2.077313] omap-gpmc 50000000.gpmc: GPMC revision 6.0
> >> [    2.083842] nand: device found, Manufacturer ID: 0x2c, Chip ID: 0xca
> >> [    2.090524] nand: Micron MT29F2G16ABAEAWP
> >> [    2.094728] nand: 256MiB, SLC, page size: 2048, OOB size: 64
> >> [    2.100745] nand: using OMAP_ECC_BCH8_CODE_HW ECC scheme
> >> [    2.109764] omap2-nand: probe of omap2-nand.0 failed with error -38
> >>
> >> OMAP NAND driver is the only user of the ELM module and we want it
> >> to be usable in all possible configurations when enabled.
> > 
> > I don't understand. Is the BCH driver optional or not?
> > 
> It is optional. If it is disabled we error out on platforms that have
> the ELM IP. But if it is enabled, we don't want to fail probe on such platforms.

Wouldn't it be better to treat the absence of the ELM driver the
same way as the absence of the ELM hardware?

> >> Let's pick either one of the below patches instead
> >>
> >> http://article.gmane.org/gmane.linux.ports.arm.omap/118488
> > 
> > This doesn't let you have the BCH driver as a module, which seems
> > wrong.
> > 
> >> http://article.gmane.org/gmane.linux.ports.arm.omap/118847
> > 
> > Looks good, although I think you can simplify this to
> > 
> > config MTD_NAND_OMAP_BCH_BUILD
> >       def_tristate MTD_NAND_OMAP2 && MTD_NAND_OMAP_BCH
> > 
> > which makes it 'm' if MTD_NAND_OMAP_BCH is set to m.
> 
> Right. I will resend this patch with this fixup
> and update the Kconfig description as well.

Ok, thanks!

	Arnd