On 17/05/16 18:46, Prakash, Prashanth wrote:
Hi Sudeep, On 5/11/2016 9:37 AM, Sudeep Holla wrote:+ +static int acpi_processor_get_lpi_info(struct acpi_processor *pr) +{ + int ret, i; + struct acpi_lpi_states_array *info; + struct acpi_device *d = NULL; + acpi_handle handle = pr->handle, pr_ahandle; + acpi_status status; + + if (!osc_pc_lpi_support_confirmed) + return -EOPNOTSUPP; + + max_leaf_depth = 0; + if (!acpi_has_method(handle, "_LPI")) + return -EINVAL; + flat_state_cnt = 0; + + while (ACPI_SUCCESS(status = acpi_get_parent(handle, &pr_ahandle))) { + if (!acpi_has_method(handle, "_LPI")) + continue; + + acpi_bus_get_device(handle, &d); + if (!strcmp(acpi_device_hid(d), ACPI_PROCESSOR_CONTAINER_HID)) + break; + + max_leaf_depth++; + handle = pr_ahandle; + } +In the above loop, we break when we find a device with HID == ACPI_PROCESSOR_CONTAINER_HID. Shouldn't we continue to parse as long as the parent HID == ACPI_PROCESSOR_CONTAINER_HID? This is required to make sure we parse states in levels higher than cluster level in processor hierarchy.
Yes, thanks for pointing that out. With just clusters in _LPI on my dev board, I missed it.
Also, I think it might be safe to break out of the loop if we didn't find _LPI package, instead of continuing. Given the presence of LPI entry: "Enabled Parent State", I can't think of a non-ambiguous scenario where we might find LPI packages in state N and N+2, but not in N+1, as we will not be able to figure out which state in N enables which states in N+2. Thoughts?
Though I admit I haven't thought in detail on how to deal with the asymmetric topology, but that was the reason why I continue instead of breaking. Excerpts from the spec: "... This example is symmetric but that is not a requirement. For example, a system may contain a different number of processors in different containers or an asymmetric hierarchy where one side of the topology tree is deeper than another...." -- Regards, Sudeep -- Regards, Sudeep -- 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
