[U-Boot] mvebu spl: translation offset set too late?

[Pierre Bourdon]

On Thu, Apr 11, 2019 at 2:07 PM Baruch Siach <baruch at tkos.co.il> wrote:
> > Note that on Turris Omnia the SPL needs a working I2C0 to fetch RAM
> > configuration from an EEPROM. The "band-aid" fix of disabling the
> > debug register write in SPL mode would break Omnia boards in 2GB RAM
> > configuration.
>
> Would it? You should be able to communicate with the EEPROM at 100KHz without
> any problem.
>
> My use case is also EEPROM access from SPL for RAM configuration on a future
> revision (2.1) of the SolidRun Armada 388 SOM. It works here with the patch
> applied.

Cc-ing Tomas who wrote the original code in the Turris u-boot fork [1]
and may have a deeper understanding of why it is needed.

My understanding from the comments and description of the patch is
that this might be i2c address dependent. I will do some more testing
tonight, but I'm almost sure that removing this code causes my Turris
Omnia to fail talking to any device on i2c0 (MCU, EEPROM, atsha204a).

[1] https://gitlab.labs.nic.cz/turris/turris-omnia-uboot/commit/590200da03fc0c04992722a50ed949981dded713

> I guess that calling dm_set_translation_offset() before spl_init would fail
> because dm_root is not initialized yet. Is that correct? I could not find the
> code that initializes dm_root. The correct fix would probably involve setting
> translation_offset at the earliest possible point.

Correct. dm_root is initialized by dm_init (look for
DM_ROOT_NON_CONST). But the way dm_init is called in SPL is via
dm_init_and_scan, which does not let boards / machine definitions
configure the translation offset before driver->bind is called.
--
Pierre Bourdon <delroth at gmail.com>
Software Engineer @ Zürich, Switzerland
https://delroth.net/