drm/msm/mdp4: flush vblank event on disable

Flush queued events when disabling the crtc. This avoids timeouts when
we come back and wait for dependencies (like the previous frame's
flip_done).

Fixes: c8afe684 ("drm/msm: basic KMS driver for snapdragon")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/569127/
Link: https://lore.kernel.org/r/20231127215401.4064128-1-dmitry.baryshkov@linaro.org

drivers/gpu/drm/msm/disp/mdp4/mdp4_crtc.c

@@ -260,6 +260,7 @@ static void mdp4_crtc_atomic_disable(struct drm_crtc *crtc,
 {
 	struct mdp4_crtc *mdp4_crtc = to_mdp4_crtc(crtc);
 	struct mdp4_kms *mdp4_kms = get_kms(crtc);
+	unsigned long flags;
 
 	DBG("%s", mdp4_crtc->name);
 
@@ -272,6 +273,14 @@ static void mdp4_crtc_atomic_disable(struct drm_crtc *crtc,
 	mdp_irq_unregister(&mdp4_kms->base, &mdp4_crtc->err);
 	mdp4_disable(mdp4_kms);
 
+	if (crtc->state->event && !crtc->state->active) {
+		WARN_ON(mdp4_crtc->event);
+		spin_lock_irqsave(&mdp4_kms->dev->event_lock, flags);
+		drm_crtc_send_vblank_event(crtc, crtc->state->event);
+		crtc->state->event = NULL;
+		spin_unlock_irqrestore(&mdp4_kms->dev->event_lock, flags);
+	}
+
 	mdp4_crtc->enabled = false;
 }