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SubjectRe: [V8 PATCH 1/3] ACPICA: Add ACPI _CLS processing
Date
On 4/24/15, 21:28, "Rafael J. Wysocki" <rjw@rjwysocki.net> wrote:

>On Friday, April 24, 2015 04:08:31 PM Suravee Suthikulpanit wrote:
>> On 4/16/15 20:45, Zheng, Lv wrote:
>> > Before back porting this to ACPICA, let me ask one simple question.
>> > According to the spec, the _CLS is optional and PCI specific.
>> > So why should we implement it in ACPICA core not OSPM specific
>>modules?
>> > If this need to be implemented in ACPICA, then what about the
>>following device identification objects?
>> > _DDN, _HRV, _MLS, _PLD, _STR, _SUN
>> >
>> > Thanks and best regards
>> > -Lv
>>
>> Hi,
>>
>> Sorry for late reply. As for the justification for introducing the _CLS
>> support in the ACPICA, this is mainly because ACPI does not currently
>> define _CID for certain device classes, which used to mostly be PCI
>> devices. Instead, ACPI spec mentioned that _CLS can be used for loading
>> generic drivers on hardware that is compatible with PCI-defined device
>> classes, but that is not implemented on the PCI bus (and is therefore
>> enumerated by ACPI.)
>
>I think it would be good to point to the particular part of the spec
>making that provision. In what section is that mentioned, exactly?

Here is the copied from section 6.1.3 _CLS (Class Code) from ACPI 5.1 spec:
"This object is used to supply OSPM with the PCI-defined class, subclass
and programming interface for a device. This object is optional but may be
useful for generic drivers written for PCI devices that move off of PCI
and are enumerated by ACPI.²

Otherwise, if the community think it¹s better to not putting the _CLS the
_CLS parsing code in ACPICA since, I can try looking into pulling the code
out of ACPICA. I also noticed a little issue in the patch series where the
ACPI_VALID_CLS is used in the patch 1 but defined in patch 2. I can send
out v9 with the fix once we agree on the _CLS parsing.

Thanks,

Suravee



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