On Mon, Sep 15, 2014 at 11:27:43AM +0300, Roger Quadros wrote:
> On 09/12/2014 07:56 PM, Ezequiel Garcia wrote:
> > On 12 Sep 12:01 PM, Roger Quadros wrote:
> >> On 09/11/2014 04:47 PM, Ezequiel Garcia wrote:
> >>> This commit adds a hidden option to build the omap_elm as a module, if
> >>> omap2_nand is a module (and similarly in the built-in case).
> >>>
> >>> This fixes the following build error when omap2_nand is chosen built-in,
> >>> and omap_elm is chosen as a module:
> >>>
> >>> drivers/built-in.o: In function `omap_nand_probe':
> >>> /work/linux-2.6/drivers/mtd/nand/omap2.c:2010: undefined reference to `elm_config'
> >>> /work/linux-2.6/drivers/mtd/nand/omap2.c:1980: undefined reference to `elm_config'
> >>> /work/linux-2.6/drivers/mtd/nand/omap2.c:1927: undefined reference to `elm_config'
> >>> drivers/built-in.o: In function `omap_elm_correct_data':
> >>> /work/linux-2.6/drivers/mtd/nand/omap2.c:1444: undefined reference to `elm_decode_bch_error_page'
> >>>
> >>> Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxxxxxxxxx>
> >>> ---
> >>> drivers/mtd/nand/Kconfig | 8 +++++++-
> >>> drivers/mtd/nand/Makefile | 2 +-
> >>> 2 files changed, 8 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
> >>> index f1cf503..12e8ee8 100644
> >>> --- a/drivers/mtd/nand/Kconfig
> >>> +++ b/drivers/mtd/nand/Kconfig
> >>> @@ -96,7 +96,7 @@ config MTD_NAND_OMAP2
> >>>
> >>> config MTD_NAND_OMAP_BCH
> >>> depends on MTD_NAND_OMAP2
> >>> - tristate "Support hardware based BCH error correction"
> >>> + bool "Support hardware based BCH error correction"
> >>> default n
> >>> select BCH
> >>> help
> >>> @@ -106,6 +106,12 @@ config MTD_NAND_OMAP_BCH
> >>> legacy OMAP families like OMAP2xxx, OMAP3xxx do not have ELM engine
> >>> so they should not enable this config symbol.
> >>>
> >>> +config MTD_NAND_OMAP_BCH_BUILD
> >>> + tristate
> >>> + depends on MTD_NAND_OMAP2
> >>> + default m if MTD_NAND_OMAP2=m && MTD_NAND_OMAP_BCH
> >>> + default y if MTD_NAND_OMAP2=y && MTD_NAND_OMAP_BCH
I think the last 2 lines could be combined:
default MTD_NAND_OMAP2 if MTD_NAND_OMAP_BCH
> >>> +
> >>> config MTD_NAND_IDS
> >>> tristate
> >>>
> >>> diff --git a/drivers/mtd/nand/Makefile b/drivers/mtd/nand/Makefile
> >>> index 4bcdeb0..3580188 100644
> >>> --- a/drivers/mtd/nand/Makefile
> >>> +++ b/drivers/mtd/nand/Makefile
> >>> @@ -27,7 +27,7 @@ obj-$(CONFIG_MTD_NAND_NDFC) += ndfc.o
> >>> obj-$(CONFIG_MTD_NAND_ATMEL) += atmel_nand.o
> >>> obj-$(CONFIG_MTD_NAND_GPIO) += gpio.o
> >>> obj-$(CONFIG_MTD_NAND_OMAP2) += omap2_nand.o
> >>> -obj-$(CONFIG_MTD_NAND_OMAP_BCH) += omap_elm.o
> >>> +obj-$(CONFIG_MTD_NAND_OMAP_BCH_BUILD) += omap_elm.o
> >>> obj-$(CONFIG_MTD_NAND_CM_X270) += cmx270_nand.o
> >>> obj-$(CONFIG_MTD_NAND_PXA3xx) += pxa3xx_nand.o
> >>> obj-$(CONFIG_MTD_NAND_TMIO) += tmio_nand.o
Apparently I came up with a nearly identical solution, so it must be
good! ;)
> >> The overall logic seems to work but I still see the following issue.
> >>
> >> In menuconfig, the OMAP_BCH option is still visible as a boolean even though
> >> the ELM module finally gets built as a module.
> >> This can be confusing to the user and I'd avoid that behaviour.
> >>
> >
> > Yes, I know. But it's either this solution or no solution at all, I think.
> >
> > Let me give some further context about this patch, so we can have more
> > information to decide.
> >
> > First of all (and IMO) the user doesn't have to know about the ELM being
> > a module or not, because modprobe will load it (since omap2_nand depends
> > on omap_elm's symbols).
> >
> > So, the new way seems a bit more intuitive for me. The user choses if he
> > wants to have hardware BCH support, and such support gets built the right
> > way.
> >
> > If we still consider this highly confusing, and we want to avoid it,
> > then it seems we can only make omap_elm a boolean, which means it'll always
> > be built-in. I crafted this patch in an effort to avoid making it boolean.
> >
> > Finally, the solution is taken from media/usb/stk1160. For good or for bad,
> > we have a precedent in doing things this way.
> >
> > Ultimately, I don't care much as I don't think anyone will build it as a module,
> > except maybe for testing the driver under probe/remove cycles.
> >
> OK. I personally prefer boolean than the Kconfig magic as it makes my life a bit
> easier and less confusing to the user i.e. wysiwyg ;).
>
> Let's see what the MTD maintainers prefer.
> Brian and David, any insights on this problem?
It seems like 'elm' serves more as an accessory piece of omap2.{o,ko},
not really a separate module, so it's possible it'd make your life even
easier to just link elm.o into omap2.o. There's no requirement that two
source files create two separate kernel modules. I think this would
present the simplest possible interface to the user.
Thoughts?
Brian
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
