[PATCH] ACPI/IORT: Fix PMCG node always look for a single ID mapping.

[Tuan Phan]

PMCG node can have zero ID mapping if its overflow interrupt
is wire based. The code to parse PMCG node can not assume it will
have a single ID mapping.

Signed-off-by: Tuan Phan <tuanphan@xxxxxxxxxxxxxxxxxxxxxx>
---
 drivers/acpi/arm64/iort.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index ed3d2d1..72444e1 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c
@@ -441,7 +441,9 @@ static int iort_get_id_mapping_index(struct acpi_iort_node *node)
 
 		return smmu->id_mapping_index;
 	case ACPI_IORT_NODE_PMCG:
-		return 0;
+		if (node->mapping_count)
+			return 0;
+		return -EINVAL;
 	default:
 		return -EINVAL;
 	}
-- 
2.7.4