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>

drivers/gpu/drm/radeon/radeon.h

@@ -2412,6 +2412,7 @@ struct radeon_device {
 	struct radeon_rlc rlc;
 	struct radeon_mec mec;
 	struct work_struct hotplug_work;
+	struct work_struct dp_work;
 	struct work_struct audio_work;
 	int num_crtc; /* number of crtcs */
 	struct mutex dc_hw_i2c_mutex; /* display controller hw i2c mutex */

drivers/gpu/drm/radeon/radeon_irq_kms.c

@@ -87,6 +87,9 @@ static void radeon_hotplug_work_func(struct work_struct *work)
 	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 @@ int radeon_irq_kms_init(struct radeon_device *rdev)
 	}
 
 	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;