drm/vkms: Annotate vblank timer

This is needed to signal the fences from page flips, annotate it
accordingly. We need to annotate entire timer callback since if we get
stuck anywhere in there, then the timer stops, and hence fences stop.
Just annotating the top part that does the vblank handling isn't
enough.
Tested-by: Melissa Wen <melissa.srw@gmail.com>
Reviewed-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Cc: linux-rdma@vger.kernel.org
Cc: amd-gfx@lists.freedesktop.org
Cc: intel-gfx@lists.freedesktop.org
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Cc: Haneen Mohammed <hamohammed.sa@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210121152959.1725404-3-daniel.vetter@ffwll.ch

drivers/gpu/drm/vkms/vkms_crtc.c

 // SPDX-License-Identifier: GPL-2.0+
 
+#include <linux/dma-fence.h>
+
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_probe_helper.h>
@@ -14,7 +16,9 @@ static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer)
 	struct drm_crtc *crtc = &output->crtc;
 	struct vkms_crtc_state *state;
 	u64 ret_overrun;
-	bool ret;
+	bool ret, fence_cookie;
+
+	fence_cookie = dma_fence_begin_signalling();
 
 	ret_overrun = hrtimer_forward_now(&output->vblank_hrtimer,
 					  output->period_ns);
@@ -49,6 +53,8 @@ static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer)
 			DRM_DEBUG_DRIVER("Composer worker already queued\n");
 	}
 
+	dma_fence_end_signalling(fence_cookie);
+
 	return HRTIMER_RESTART;
 }