drm/amd/display: Add dmub hpd sense callback

[WHY]
HPD sense notification has been implemented in DMUB, which
can occur during low power states and need to be
notified from firmware to driver.

[HOW]
Define callback and register new HPD sense notification.
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Roman Li <Roman.Li@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -807,6 +807,20 @@ static void dmub_hpd_callback(struct amdgpu_device *adev,
 	}
 }
 
+/**
+ * dmub_hpd_sense_callback - DMUB HPD sense processing callback.
+ * @adev: amdgpu_device pointer
+ * @notify: dmub notification structure
+ *
+ * HPD sense changes can occur during low power states and need to be
+ * notified from firmware to driver.
+ */
+static void dmub_hpd_sense_callback(struct amdgpu_device *adev,
+			      struct dmub_notification *notify)
+{
+	DRM_DEBUG_DRIVER("DMUB HPD SENSE callback.\n");
+}
+
 /**
  * register_dmub_notify_callback - Sets callback for DMUB notify
  * @adev: amdgpu_device pointer
@@ -3808,6 +3822,12 @@ static int register_hpd_handlers(struct amdgpu_device *adev)
 			DRM_ERROR("amdgpu: fail to register dmub hpd callback");
 			return -EINVAL;
 		}
+
+		if (!register_dmub_notify_callback(adev, DMUB_NOTIFICATION_HPD_SENSE_NOTIFY,
+			dmub_hpd_sense_callback, true)) {
+			DRM_ERROR("amdgpu: fail to register dmub hpd sense callback");
+			return -EINVAL;
+		}
 	}
 
 	list_for_each_entry(connector,

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h

@@ -50,7 +50,7 @@
 
 #define AMDGPU_DM_MAX_NUM_EDP 2
 
-#define AMDGPU_DMUB_NOTIFICATION_MAX 6
+#define AMDGPU_DMUB_NOTIFICATION_MAX 7
 
 #define HDMI_AMD_VENDOR_SPECIFIC_DATA_BLOCK_IEEE_REGISTRATION_ID 0x00001A
 #define AMD_VSDB_VERSION_3_FEATURECAP_REPLAYMODE 0x40