[PATCH] drm/amdgpu: Document amdgpu_crtc->otg_inst and ->event fields

[sunpeng.li at amd.com]

From: Leo Li <sunpeng.li at amd.com>

These two fields are used by DC, and their purposes are not immediately
clear.

Signed-off-by: Leo Li <sunpeng.li at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
index f91a9bd..dd4366c 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mode.h
@@ -434,7 +434,27 @@ struct amdgpu_crtc {
 	struct hrtimer vblank_timer;
 	enum amdgpu_interrupt_state vsync_timer_enabled;
 
+	/**
+	 * @otg_inst:
+	 *
+	 * DC output timing generator instance used by this CRTC.
+	 *
+	 * This is used to search for a corresponding amdgpu_crtc, given
+	 * the OTG instance. An example is interrupt handlers, where the handler
+	 * is provided the OTG instance.
+	 */
 	int otg_inst;
+
+	/**
+	 * @event:
+	 *
+	 * Vblank event, made to reference the new CRTC state's vblank event
+	 * during plane commit. It's used by the DC page flip interrupt handler
+	 * to call drm_crtc_send_vblank_event().
+	 *
+	 * This is needed since the current CRTC state at the time of pflip
+	 * interrupt may not be the same as the one used during plane commit.
+	 */
 	struct drm_pending_vblank_event *event;
 };
 
-- 
2.7.4