[U-Boot] [PATCH 3/4] spi: omap3: Convert to DM

[Simon Glass]

+Hans

Hi Tom,

On 21 January 2016 at 05:24, Tom Rini <trini at konsulko.com> wrote:
> On Wed, Jan 20, 2016 at 07:46:15PM -0700, Simon Glass wrote:
>> +Mugunthan, Tom
>>
>> On 17 January 2016 at 03:56, Christophe Ricard
>> <christophe.ricard at gmail.com> wrote:
>> > Convert omap3_spi driver to DM and keep compatibility with previous
>> > mode.
>> >
>> > Signed-off-by: Christophe Ricard <christophe-h.ricard at st.com>
>> > ---
>> >
>> >  drivers/spi/Kconfig     |   6 +
>> >  drivers/spi/omap3_spi.c | 439 ++++++++++++++++++++++++++++++++++++++++++------
>> >  drivers/spi/omap3_spi.h |  14 +-
>> >  3 files changed, 402 insertions(+), 57 deletions(-)
>>
>> This is a pretty painful conversion, with lots of #ifdefs. I think it
>> would be possible to use a common pointer type and reduce this.
>>
>> But perhaps it does not matter - how long must we be in the state of
>> supporting legacy SPI? Can we convert all TI boards to driver model?
>
> We _really_ need some way to support more than one board per binary
> before we can move everything to DM only.
>
> I think we can kind of do this today if we stick to using platform data
> for everything that's board-specific rather than SoC-defined.  What we
> talked about at ELCE was auto-generating the pdata from the device tree,
> I think.

We discussed this on IRC but since that doesn't exist as far as the
mailing list is concerned...

The current plan is:

- Adjust build system to optionally build a u-boot.img in FIT format
that includes the U-Boot binary and >1 device tree files
- Adjust SPL to load this
- Add a way for SPL to determine which device tree to select (by
calling a board-specific function)
- Have SPL pass this selected device tree to U-Boot when it starts

Thus we should be able to support more than one board with a single
U-Boot image. Of course this is not a perfect solution (e.g. it is
inefficient since the DTs are likely to be largely the same) but it
should be a good first step.

I'm going to try this out with sunxi initially and plan to get some
patches out by the end of the week.

Regards,
Simon