Hi Simon,
On 12.04.19 14:35, Simon Glass wrote:
Hi,
On Thu, 11 Apr 2019 at 06:55, Stefan Roese sr@denx.de wrote:
Adding Simon to Cc (again)...
On 11.04.19 14:26, Pierre Bourdon wrote:
On Thu, Apr 11, 2019 at 2:07 PM Baruch Siach baruch@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/590200da03fc0c04...
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.
I also see no easy way to solve this "hen egg problem" with the translation offset before bind for the drivers is being called with the current API. Perhaps Simon (or someone else) has an idea?
As mentioned in my earlier reply, moving to a callback from the DM code into a board specific code or using a Kconfig option could solve this issue.
I don't like dm_set_translation_offset() very much. As some said, you have to call it after DM is up but before any affected drivers are bound. Tricky.
Yes. We missing this very important fact while implementing this solution.
How about adding a field in global_data, which can be set early, them have dm_init() pick it up?
Okay. I could come up with a patch for this quickly, I think. I would prefer to add a Kconfig option for this, to not add size to GD for platforms not needed this option. This could also save a bit of SPL size as well.
Let me see...
Thanks, Stefan