[U-Boot] IMX6 DM_USB / DM_MMC requires OF_CONTROL?

[Fabio Estevam]

Hi Tim,

On Tue, Feb 19, 2019 at 4:11 PM Tim Harvey <tharvey at gateworks.com> wrote:

> Fabio / Stefano,
>
> Thanks for your quick response. Yes, I've been looking at the
> mx6sabreauto conversion series and trying to plot a course for my
> boards that won't completely thrash users - we need backwards
> compatibility.
>
> We currently have a large list of IMX6 boards with different dtbs
> (about 10 boards in total resulting in 20 dtbs b/c of the imx6q vs
> imx6dl options). These currently are all covered by a single
> SPL/U-Boot binary of board/gateworks/gw_ventana and not using
> OF_CONTROL (as its relatively new for IMX6 and these boards have been
> around for many years now). Boot scripts are setup to load the DTB
> from the root filesystem which varies per OS between a ubi volume or
> ext filesytem.
>
> So it looks like what I need to do is add all my device-tree's from
> the kernel to U-Boot's arch/arm/dts, add SPL_MULTI_DTB_FIT support and
> a board_fit_config_name_match() function for the SPL to pick the right
> DTB. Some questions come to mind:
>
> 1. Where would I apply any fixup's to the DTBs before they are used by the SPL?
>
> 2. I'm assuming the FIT image is embedded within the SPL and thus does
> not require specific storage/filesystem support?
>
> 3. Users are used to being able to update the DTB's used by Linux by
> updating them on the filesystem - does all of this give the user the
> option of using either the DTB that U-Boot uses vs the DTB that
> already exists on one of the partitions? If the bootscripts already
> load a DTB from a filesystem does U-Boot's ft_board_setup() still
> function normally?

I don't have the answers to your questions. Added some folks who could
probably help.

When it comes to U-Boot DM, I am still at the beginner level :-)