[MinnowBoard] Board file

[Darren Hart]

On 5/10/16 9:21 AM, Tony Makkiel wrote:
> 
> 
> On 10/05/16 16:03, Darren Hart wrote:
>>
>>
>> On 5/10/16 5:39 AM, Tony Makkiel wrote:
>>> Hi,
>>>      Where can I find minnowboard board files? According to
>>> http://events.linuxfoundation.org/sites/events/files/slides/x86-platform.pdf
>>>
>>> they should be at
>>> drivers/platform/x85/minnowboard* .
>>
>> Well.... that wasn't quite the point of that presentation :-) If you
>> haven't watched the video that goes with it, I'd recommend doing that.
>>
> I found the link from Google. Did not know there was a video file. Do
> you have a link for it please?

https://www.youtube.com/watch?v=IZuNCN7wkqs

>> Ultimately, the Minnowboard v1 patches were not accepted to the mainline
>> Linux kernel because they were board files, and the proper solution is
>> to provide the platform information via the firmware. We have been
>> working on the ACPI specification to enable this feature (see ACPI _DSD
>> which was added for this purpose), and are still working on a standard
>> mechanism to provide user-created ACPI DSDT overlays. That work is not
>> yet complete.
>>
> 
> What is the name used by firmware in minnowboard? Probably , I can use
> the same name for my driver in ACPI initialization to verify probe works.

Sorry, I don't understand the question. Name for what?

>> There are some workarounds in place, perhaps John H. can comment on the
>> current state of those.
>>
>>>
>>>      I am on kernel 4.5 and cant see any similar files. I am writing an
>>> i2c driver using minnowboard as host. But not sure where to register the
>>> device so that the device driver gets probed. I would prefer ACPI. But I
>>> think I would need to modify the firmware to do that (Do I? If I have to
>>> access to firmware might be a problem).
>>>      At present, I am using i2c_new_device within the driver
>>> module_init.
>>> But am not sure what the proper way to do it is?
>>
>> I suggest having a look at the example i2c driver in the minnowboard
>> extras repository.
>>
>> https://github.com/MinnowBoard/minnow-max-extras/tree/master/modules/i2c
> 
> The example also use i2c_new_device. But the problem is, it assumes the
> driver know the i2c id (i2c_get_adapter(0)). I want the driver to be
> generic, so that if I use it on another platform with a different bus
> id, it still gets probed.

Right, and what you describe is the right way to do it, but does require
you do one of the following:

1) Rebuild the firmware with your updated ACPI tables.
2) Use one of the workarounds mentioned above
3) Wholesale replace the DSDT per the Linux kernel development initramfs
mechanism

1-3 likely also require you to update some of the drivers to understand
that description, or use the new "device_properties" Linux kernel interface.


> 
>>
>> This is for the MinnowBoard MAX and Turbot boards, not the MinnowBoard
>> v1, but conceptually it applies equally.
>>
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-- 
Darren Hart
Intel Open Source Technology Center