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SubjectRe: [V8 PATCH 1/3] ACPICA: Add ACPI _CLS processing
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.)

The code introduced for supporting _CLS is also similar in the way
ACPICA is currently parsing the _CID or _SUB (which are also optional),
and using it for the same purpose of identifying devices for loading
drivers.

Also, since this method for identifying devices is OS-independent, I
believe this should not be done in the OSPM specific modules.

Thanks,

Suravee


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