[U-Boot] [PATCH v2 00/32] spi: DM_SPI migration timeout, remainder(2)

[Stefano Babic]

Hi Jagan,

(CCing the world looks to me quite a terror attack, nevertheless):

On 27/11/18 06:51, Jagan Teki wrote:
> On Mon, Nov 26, 2018 at 12:48 PM Peng Fan <peng.fan at nxp.com> wrote:
>>
>> Hi Jagan,
>>
>> Just have a quick question here.
>>
>> After dropping non-DM code, for SPL use non-DM code should switch to SPL_DM and use SPL OF CONTROL?
> 

I can understand the reasons to switch completely to DM code, but let's
face some real facts:

- dropping legacy code requires to use SPL_OF_CONTROL into SPL, and yes,
footprint steadily increases. We are getting rid of place for MX6 Solo,
and this is not an ancient processor we can forget.
Size of SRAM is not something we can discuss - it is. Other features
(secure boot, etc.) were pushed to SPL, and these features were
requested by real projects. We cannot get rid of these feature just to
make place for DM.

- the benefits cannot be really understood by the manufacturers or
owners of boards, because they can see a step in the past if they have
to forget some features they are currently using.

- TPL adds an additional step and this increases the boottime - another
*real* and *important* feature for most projects.

> Here are the options, that we dealt based on the size constraints
> 1) try to use DM_SPL with SPL OF_CONTROL

There is no enough place for most SOCs, even quite recent. This is not
due just to the size of SRAM, but also by some restriction on the usage
of the SRAM itself by the internal BootROM.

> 2) try PLATDATA

This is even not footprint friendly.

> 3) try TPL for truly small size
> 

See above. There is an additional layer without evident advantages for
manufacturers and / or customers.

> if none works, we can see the other option. may be some glue code to
> read flash for SPL or something else.
> 

Best regards,
Stefano

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