ACPI / thermal: Add check of "_TZD" availability and evaluating result

Some machines don't provide _TZD, so check the availability of it
before carrying out futher operations.

If _TZD is present, also check the result of its evaluation.

[rjw: Changelog]
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/drivers/acpi/thermal.c b/drivers/acpi/thermal.c
index ccf9527d7ed3..0055c83c26c0 100644
--- a/drivers/acpi/thermal.c
+++ b/drivers/acpi/thermal.c
@@ -485,14 +485,14 @@ static int acpi_thermal_trips_update(struct acpi_thermal *tz, int flag)
                         break;
         }
 
-        if (flag & ACPI_TRIPS_DEVICES) {
-                memset(&devices, 0, sizeof(struct acpi_handle_list));
+        if ((flag & ACPI_TRIPS_DEVICES)
+            && acpi_has_method(tz->device->handle, "_TZD")) {
+                memset(&devices, 0, sizeof(devices));
                 status = acpi_evaluate_reference(tz->device->handle, "_TZD",
                                                 NULL, &devices);
-                if (memcmp(&tz->devices, &devices,
-                                sizeof(struct acpi_handle_list))) {
-                        memcpy(&tz->devices, &devices,
-                                sizeof(struct acpi_handle_list));
+                if (ACPI_SUCCESS(status)
+                    && memcmp(&tz->devices, &devices, sizeof(devices))) {
+                        tz->devices = devices;
                         ACPI_THERMAL_TRIPS_EXCEPTION(flag, "device");
                 }
         }