On Tue, 2012-05-29 at 22:27 +0000, Moore, Robert wrote: > > > 2. Calling acpi_get_handle() on _OST prior to executing the method. > > > This will ensure that this method only gets run if it is present > > under > > > the device in question. Coupled with what is already outlined in #1 > > > above, now _OST gets executed only when it is defined under the > > device object. > > > Example case in the existing code, please see > > acpi_processor_ppc_ost() > > > implementation. > > > > Yes, I did look at acpi_processor_ppc_ost() when I implemented the > > function. I believe calling acpi_get_handle() is redundant since > > acpi_ns_get_node() is called within acpi_evaluate_object() as well. > > acpi_evaluate_object() simply returns with AE_NOT_FOUND when _OST > > method does not exist. > > > > This is correct. If _OST does not exist, AE_NOT_FOUND will be returned from evaluate_object. Yes that is correct from the ACPI Spec and implementation point of view. My thinking is that a call to acpi_get_handle() might not penalize the OS as much as acpi_evaluate_object() would on systems that don't actually implement _OST. In other words, acpi_get_handle() might not go as deep as acpi_evaluate_object() would go into the ACPI layer, hence might be a safer measure on platforms that don't actually implement this optional method under all devices included in this patch set. -- Shuah -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
