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 <[e-mail]>
Reviewed-by: Alex Deucher <[e-mail]>
Acked-by: Huang Rui <[e-mail]>
Signed-off-by: Alex Deucher <[e-mail]>

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

···
 
 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

···
 #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"
···
 {
 	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;
 }