radeon: introduce a dp_work handler

This is to be called on short HPD irqs, just introduce
the basic infrastructure for it.

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/radeon_irq_kms.c b/drivers/gpu/drm/radeon/radeon_irq_kms.c
index 00fc597..e82ae81 100644
--- a/drivers/gpu/drm/radeon/radeon_irq_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_irq_kms.c
@@ -87,6 +87,9 @@
 	drm_helper_hpd_irq_event(dev);
 }
 
+static void radeon_dp_work_func(struct work_struct *work)
+{
+}
 /**
  * radeon_driver_irq_preinstall_kms - drm irq preinstall callback
  *
@@ -276,6 +279,7 @@
 	}
 
 	INIT_WORK(&rdev->hotplug_work, radeon_hotplug_work_func);
+	INIT_WORK(&rdev->dp_work, radeon_dp_work_func);
 	INIT_WORK(&rdev->audio_work, r600_audio_update_hdmi);
 
 	rdev->irq.installed = true;