[U-Boot] [PATCH 3/4] mx6ul_14x14_evk: Remove CONFIG_SPL_FAT_SUPPORT

[Fabio Estevam]

Hi Peng,

On Wed, Sep 9, 2015 at 10:33 AM, Peng Fan <b51431 at freescale.com> wrote:

> Fabio and Stefano,
>
> I agree that we have a common way for Freescale boards. But why
> not choose SPL_FAT? In future we may add QSPI or SPI SPL boot, then we

We have boards that boot from SPI SPL today and this is well supported.

> also need to burn u-boot.img as a raw image to sd card?

You had to write SPL as raw image, so you can do the same for
u-boot.img for a more standard behaviour across different boards.

Also, you prefer FAT for storing u-boot.img, but why not EXT3 or EXT4?
We all know this is very flexible and vaild options, but we are trying
to keep things consistent.

or burn it
> to spi/qspi chips? I think the easy way is FAT load from mmc.

SPI is another story and it is well supported today in SPL. You just
need to write SPL at offset 1k and u-boot.img at offset
CONFIG_SYS_SPI_U_BOOT_OFFS (usually 64kB so that it starts in a sector
boundary).

> Also see the following,
> #define CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR 138 /* offset 69KB */
> #define CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS      800 /* 400 KB */
> #define CONFIG_SYS_MMCSD_FS_BOOT_PARTITION      1
> #define CONFIG_SYS_MONITOR_LEN  (CONFIG_SYS_U_BOOT_MAX_SIZE_SECTORS/2*1024)
>
> It u-boot.img is bigger than 400KB, we also need to change the macro definitions,
> why not choose FAT and we do not need to care about that u-boot.img may be bigger
> than 400KB, right? And 400KB is a fixed size, whether u-boot.img is saying 100KB or 200KB.

The size constraint also exists when you boot from a FAT partition as
you need to decide on the partition size for the FAT area.

The main point here is to be able to use the same solution for many
boards as possible.

Peter Robinson put a lot of effort into moving the config options into
mx6_common.h.

If we start to store u-boot.img in a FAT partition only for this mx6ul
evk board that would be a step in the opposite direction of
consolidation.

> In future, if our mfgtool need to support SPL, each time we need to modify related macro in uboot,
> we need to uppdate mfgtool. We suffer for changing both.

mfgtool is not the only tool out there and I see no reason why it
can't flash u-boot.img in a raw partition.

Regards,

Fabio Estevam