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

[Peng Fan]

Hi Simon,

On Mon, Jan 25, 2016 at 06:11:24PM -0700, Simon Glass wrote:
>+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

Can dtb be sperated from the final u-boot.img, if using SPL?
I mean let SPL load the u-boot.img and the dtb to correct DRAM address.
And the dtb is shared with linux kernel.

Regards,
Peng.
>
>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
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