[PATCH v1] ACPI: TAD: Use DC wakeup only if AC wakeup is supported

["Rafael J. Wysocki" <rafael@kernel.org>]

From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

According to Section 9.17.2 of ACPI 6.6 [1], setting ACPI_TAD_DC_WAKE in
the capabilities without setting ACPI_TAD_AC_WAKE is invalid, so don't
support wakeup if that's the case.

Moreover, it is sufficient to check ACPI_TAD_AC_WAKE alone to determine
if wakeup is supported at all, so use this observation to simplify one
check.

Link: https://uefi.org/specs/ACPI/6.6/09_ACPI_Defined_Devices_and_Device_Specific_Objects.html#gcp-get-capability [1]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---

This change is on top of linux-next.

---
 drivers/acpi/acpi_tad.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/acpi/acpi_tad.c
+++ b/drivers/acpi/acpi_tad.c
@@ -706,6 +706,9 @@ static int acpi_tad_probe(struct platfor
 		caps &= ~(ACPI_TAD_AC_WAKE | ACPI_TAD_DC_WAKE);
 	}
 
+	if (!(caps & ACPI_TAD_AC_WAKE))
+		caps &= ~ACPI_TAD_DC_WAKE;
+
 	dd = devm_kzalloc(dev, sizeof(*dd), GFP_KERNEL);
 	if (!dd)
 		return -ENOMEM;
@@ -719,7 +722,7 @@ static int acpi_tad_probe(struct platfor
 	 * runtime suspend.  Everything else should be taken care of by the ACPI
 	 * PM domain callbacks.
 	 */
-	if (ACPI_TAD_AC_WAKE | ACPI_TAD_DC_WAKE) {
+	if (ACPI_TAD_AC_WAKE) {
 		device_init_wakeup(dev, true);
 		dev_pm_set_driver_flags(dev, DPM_FLAG_SMART_SUSPEND |
 					     DPM_FLAG_MAY_SKIP_RESUME);