[PATCH 2/2] ACPI / PPTT: use ACPI ID whenever ACPI_PPTT_ACPI_PROCESSOR_ID_VALID is set

[Manoj Iyer]

From: Sudeep Holla <Sudeep.Holla at arm.com>

Currently, we use the ACPI processor ID only for the leaf/processor nodes
as the specification states it must match the value of the ACPI processor
ID field in the processor’s entry in the MADT.

However, if a PPTT structure represents a processors group, it
matches a processor container UID in the namespace and the
ACPI_PPTT_ACPI_PROCESSOR_ID_VALID flag indicates whether the
ACPI processor ID is valid.

Let's use UID whenever ACPI_PPTT_ACPI_PROCESSOR_ID_VALID is set to be
consistent instead of using table offset as it's currently done for
non-leaf nodes.

Fixes: 2bd00bcd73e5 (ACPI/PPTT: Add Processor Properties Topology Table parsing)

BugLink: http://launchpad.net/bugs/1797200

Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
Acked-by: Jeremy Linton <jeremy.linton at arm.com>
[ rjw: Changelog (minor) ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
(cherry picked from commit 30998033f62a9915e0f884d680569a39bc9ce133)
Signed-off-by: Manoj Iyer <manoj.iyer at canonical.com>
---
 drivers/acpi/pptt.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/pptt.c b/drivers/acpi/pptt.c
index e5ea1974d1e3..d1e26cb599bf 100644
--- a/drivers/acpi/pptt.c
+++ b/drivers/acpi/pptt.c
@@ -481,8 +481,14 @@ static int topology_get_acpi_cpu_tag(struct acpi_table_header *table,
 	if (cpu_node) {
 		cpu_node = acpi_find_processor_package_id(table, cpu_node,
 							  level, flag);
-		/* Only the first level has a guaranteed id */
-		if (level == 0)
+		/*
+		 * As per specification if the processor structure represents
+		 * an actual processor, then ACPI processor ID must be valid.
+		 * For processor containers ACPI_PPTT_ACPI_PROCESSOR_ID_VALID
+		 * should be set if the UID is valid
+		 */
+		if (level == 0 ||
+		    cpu_node->flags & ACPI_PPTT_ACPI_PROCESSOR_ID_VALID)
 			return cpu_node->acpi_processor_id;
 		return ACPI_PTR_DIFF(cpu_node, table);
 	}
-- 
2.17.1