[U-Boot] [RFC PATCH v1 0/9] Add support for applications of overlays in SPL

[Michal Simek]

On 29. 03. 19 13:50, Jean-Jacques Hiblot wrote:
> 
> On 29/03/2019 11:26, Michal Simek wrote:
>> On 29. 03. 19 11:13, Jean-Jacques Hiblot wrote:
>>> On 28/03/2019 14:54, Michal Simek wrote:
>>>> On 25. 03. 19 9:08, Michal Simek wrote:
>>>>> On 22. 03. 19 15:39, Jean-Jacques Hiblot wrote:
>>>>>> The purpose of this series is to provide the SPL with ability to
>>>>>> apply
>>>>>> overlays for u-boot. this is only a RFC so far, to get a feedback on
>>>>>> the
>>>>>> approach.
>>>>>>
>>>>>> Our use-case is the support of the daughter boards of the AM65x
>>>>>> EVM. In
>>>>>> Linux, each board is supported by a unique overlay. The presence
>>>>>> of the
>>>>>> boards is detected at runtime, and some useful features (like USB)
>>>>>> are
>>>>>> implemented on those daughter boards. Instead of providing multiple
>>>>>> dtbs
>>>>>> and fall in a combinatorial pit, we propose to use DT overlays.
>>>>> Not sure if you have it on these boards too but I expect you are
>>>>> able to
>>>>> detect base board with this code board/ti/common/board_detect.c
>>>>>
>>>>> How do you detect these daughter cards? Is there additional I2C
>>>>> connection to them and they have on board eeprom with any format for
>>>>> detection?
>>> Yes. There is EEPROM and GPIOs involved in the detection process.
>> Does that mean that you use gpio bitbanging i2c eeprom to read
>> information?
> no, on am65 we use GPIOs and a true I2C to detect the daughter boards

ok.

>> x
>>
>>>>> Something similar what it is part of FMC standard/VITA 57.1 with using
>>>>> FRU spec for daughter card description?
>>>>> Anyway we are working on FRU parser exactly for this purpose.
>>>>>
>>>>> Do you also need to apply that overlays in SPL?
>>> We need to apply in SPL so that u-boot has the right information in
>>> the DT.
>>>>> Isn't it enough to apply them as the part of board_fdt_blob_setup()?
>>> No it's possible to do that in board_fdt_blob_setup().
>> A little bit confused by your response. yes/no?
> I forgot a key word here. it is not possible. board_fdt_blob_setup is
> used to provide a DTB blob

ok. Will play with this and will see.

Thanks,
Michal