Hi Rafael,
On 5/10/2017 8:46 PM, Rafael J. Wysocki wrote:
>> My proposal was to require platform AML code to indicate the dependencies
>> between GED and drivers on the right side of the picture via _DEP as this
>> cannot be done via normal kernel mechanisms.
> Something like _DEP would be needed.
>
> However, _DEP as specified is only about operation region dependencies, which
> doesn't seem to be applicable here.
>
> That said, _DEP is used for general dependecies by firmware already, but it
> would at least be good to send a proposal for a spec update regarding that
> before mandating using _DEP for GED.
OK. I'll reach out to Harb and let's see where the proposal goes.
>
>> This approach might work in general. However, it also has its own caveats.
>>
>> All of these drivers on the right side are unrelated to each other. Some
>> operating system can implement a subset of these drivers.
>>
>> If I include the dependencies, GED will never load for partial driver situations.
>> This is also a deal breaker.
> _DEP doesn't mean a hard dependency AFAICS. It is about ordering, not about
> presence, at least as specified currently.
>
>> Why would you break some other feature if your OS doesn't support RAS as an
>> example?
>>
>> Given all these lose bindings and no driver association, where do we go
>> from here?
>>
>> I consider GED as a light version of Embedded controller (EC) implementation.
> No, it is not.
Thanks for correction. Let me repeat with the correct terminology this time.
Don't we have the same problem on GPE/SCI mechanism?
An event that SCI is delivering may not be handled because the handler of the
event is not present during OS boot?
The SCI relationship would be:
| SCI | <---> | Platform specific ACPI AML (_AEI) | <----> Vendor XYZ driver
<----> Vendor I2C
<----> ACPI GHES
>
> It is more of a generalization of the GPE/SCI mechanism in order to make it
> possible to cover things different from GPIO (which already is covered by
> _AEI).
>
>> How is this problem solved for EC as it has the same problem?
> It doesn't. The EC relies on the GPE/SCI mechanism to be there and that is
> always present.
>
> Thanks,
> Rafael
--
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
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