drm/amdgpu: add s0i3 capacity check for s0i3 routine (v2)

add amdgpu_acpi_is_s0ix_supported() to check the platform
whether support s0i3.

v2: fix empty function parameters warning (void)
Signed-off-by: Prike Liang <Prike.Liang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu.h

@@ -1311,9 +1311,11 @@ int amdgpu_acpi_pcie_notify_device_ready(struct amdgpu_device *adev);
 
 void amdgpu_acpi_get_backlight_caps(struct amdgpu_device *adev,
 		struct amdgpu_dm_backlight_caps *caps);
+bool amdgpu_acpi_is_s0ix_supported(void);
 #else
 static inline int amdgpu_acpi_init(struct amdgpu_device *adev) { return 0; }
 static inline void amdgpu_acpi_fini(struct amdgpu_device *adev) { }
+static inline bool amdgpu_acpi_is_s0ix_supported(void) { return false; }
 #endif
 
 int amdgpu_cs_find_mapping(struct amdgpu_cs_parser *parser,

drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c

@@ -27,6 +27,7 @@
 #include <linux/power_supply.h>
 #include <linux/pm_runtime.h>
 #include <acpi/video.h>
+#include <acpi/actbl.h>
 
 #include <drm/drm_crtc_helper.h>
 #include "amdgpu.h"
@@ -894,3 +895,16 @@ void amdgpu_acpi_fini(struct amdgpu_device *adev)
 	unregister_acpi_notifier(&adev->acpi_nb);
 	kfree(adev->atif);
 }
+
+/**
+ * amdgpu_acpi_is_s0ix_supported
+ *
+ * returns true if supported, false if not.
+ */
+bool amdgpu_acpi_is_s0ix_supported(void)
+{
+	if (acpi_gbl_FADT.flags & ACPI_FADT_LOW_POWER_S0)
+		return true;
+
+	return false;
+}