[U-Boot] [PATCH 0/3] SPL: move CONFIG_SPL_*_LOAD to Kconfig

[Tom Rini]

On Tue, Dec 06, 2016 at 02:48:27PM +0100, Fabien Parent wrote:

> Moving to CONFIG_SPL_*_LOAD options to Kconfig offers several advantage:
>  * simpler config headers
>  * on some boards we can easily switch to another boot media without needing
>    to modify the config headers.
> 
> This series fixes an issue in davinci where a wrong option was used in place
> of a CONFIG_SPL_*_LOAD option, then move the options to Kconfig options, and
> finally start using these Kconfig options for the OMAPL138-LCDK board.
> 
> Fabien Parent (3):
>   davinci: spl: use correct macro to select boot device
>   SPL: create Kconfig options for CONFIG_SPL_*_LOAD
>   davinci: omapl138_lcdk: use new CONFIG_SPL_*_LOAD Kconfig options
> 
>  arch/arm/mach-davinci/spl.c     |  2 +-
>  common/spl/Kconfig              | 25 +++++++++++++++++++++++++
>  configs/omapl138_lcdk_defconfig |  1 +
>  include/configs/omapl138_lcdk.h |  2 --
>  scripts/config_whitelist.txt    |  3 ---
>  5 files changed, 27 insertions(+), 6 deletions(-)

So, I think this shows that some of the SPL framework needs to be
revisited for davinci.  First, lets make it clear what
CONFIG_SPL_{SPI,NAND,MMC}_LOAD is doing.

CONFIG_SPL_MMC_LOAD is used to flag that on davinci we're loading U-Boot
from MMC.  It's not set / used today but I assume it was working when I
introduced all of this.

CONFIG_SPL_NAND_LOAD is used for two things.  First, it is used to flag
that on davinci we're loading U-Boot from NAND.  Second, it is used to
enable the non-SPL_FRAMEWORK NAND driver
(drivers/mtd/nand/nand_spl_load.c).  This driver is not used on davinci.

CONFIG_SPL_SPI_LOAD is used for two things.  First, it is used to flag
that on davinci we're loading U-Boot from SPI flash.  Second, it used
globally to enable common/spl/spl_spi.c.

NAND boot is done here via CONFIG_SPL_NAND_SIMPLE which is the regular
SPL framework based NAND driver (drivers/mtd/nand/nand_spl_simple.c).
This also means that the patch to update CONFIG_SYS_NAND_U_BOOT_SIZE was
not needed since we don't use that driver.

Now, I think that in retrospect
arch/arm/mach-davinci/spl.c::spl_boot_device could be re-worked to key
off of CONFIG_SPL_NAND_SIMPLE / CONFIG_SPL_SPI_SUPPORT / SPL_MMC_SUPPORT.

And a good but possibly complex series would be to consolidate the usage
of SPL_SPI_SUPPORT, SPL_SPI_FLASH_SUPPORT and SPL_SPI_LOAD just in to
SPL_SPI_SUPPORT.  I'll probably try and do this myself as there's a ton
of build testing and size checking to make sure nothing odd breaks here
to do.

-- 
Tom
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