drm/omapdrm: Annotate dma-fence critical section in commit path

Nothing special, just put the end right after hw_done(). Note that in
one path there's a wait for the flip/update to complete. But as far as
I understand from comments and code that's only relevant for modesets,
and skipped if there wasn't a modeset done on a given crtc.

For a bit more clarity pull the hw_done() call out of the if/else,
that way it's a bit clearer flow. But happy to shuffle this around as
is seen fit.
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210121152959.1725404-9-daniel.vetter@ffwll.ch

drivers/gpu/drm/omapdrm/omap_drv.c

@@ -68,6 +68,7 @@ static void omap_atomic_commit_tail(struct drm_atomic_state *old_state)
 {
 	struct drm_device *dev = old_state->dev;
 	struct omap_drm_private *priv = dev->dev_private;
+	bool fence_cookie = dma_fence_begin_signalling();
 
 	dispc_runtime_get(priv->dispc);
 
@@ -90,8 +91,6 @@ static void omap_atomic_commit_tail(struct drm_atomic_state *old_state)
 		omap_atomic_wait_for_completion(dev, old_state);
 
 		drm_atomic_helper_commit_planes(dev, old_state, 0);
-
-		drm_atomic_helper_commit_hw_done(old_state);
 	} else {
 		/*
 		 * OMAP3 DSS seems to have issues with the work-around above,
@@ -101,10 +100,12 @@ static void omap_atomic_commit_tail(struct drm_atomic_state *old_state)
 		drm_atomic_helper_commit_planes(dev, old_state, 0);
 
 		drm_atomic_helper_commit_modeset_enables(dev, old_state);
-
-		drm_atomic_helper_commit_hw_done(old_state);
 	}
 
+	drm_atomic_helper_commit_hw_done(old_state);
+
+	dma_fence_end_signalling(fence_cookie);
+
 	/*
 	 * Wait for completion of the page flips to ensure that old buffers
 	 * can't be touched by the hardware anymore before cleaning up planes.