drm/msm/atomic: Switch to vblank_start helper

Drop our custom thing and switch to drm_crtc_next_vblank_start() for
calculating the time of the start of the next vblank period.

Signed-off-by: Rob Clark <[e-mail]>
Patchwork: https://patchwork.freedesktop.org/patch/525819/
Link: https://lore.kernel.org/r/[e-mail]

drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c

···
 	pm_runtime_put_sync(&dpu_kms->pdev->dev);
 }
 
-static ktime_t dpu_kms_vsync_time(struct msm_kms *kms, struct drm_crtc *crtc)
-{
-	struct drm_encoder *encoder;
-
-	drm_for_each_encoder_mask(encoder, crtc->dev, crtc->state->encoder_mask) {
-		ktime_t vsync_time;
-
-		if (dpu_encoder_vsync_time(encoder, &vsync_time) == 0)
-			return vsync_time;
-	}
-
-	return ktime_get();
-}
-
 static void dpu_kms_prepare_commit(struct msm_kms *kms,
 		struct drm_atomic_state *state)
 {
···
 	.irq             = dpu_core_irq,
 	.enable_commit   = dpu_kms_enable_commit,
 	.disable_commit  = dpu_kms_disable_commit,
-	.vsync_time      = dpu_kms_vsync_time,
 	.prepare_commit  = dpu_kms_prepare_commit,
 	.flush_commit    = dpu_kms_flush_commit,
 	.wait_flush      = dpu_kms_wait_flush,

drivers/gpu/drm/msm/msm_atomic.c

···
 	struct msm_kms *kms = priv->kms;
 	struct drm_crtc *async_crtc = NULL;
 	unsigned crtc_mask = get_crtc_mask(state);
-	bool async = kms->funcs->vsync_time &&
-			can_do_async(state, &async_crtc);
+	bool async = can_do_async(state, &async_crtc);
 
 	trace_msm_atomic_commit_tail_start(async, crtc_mask);
 
···
 
 			kms->pending_crtc_mask |= crtc_mask;
 
-			vsync_time = kms->funcs->vsync_time(kms, async_crtc);
+			if (drm_crtc_next_vblank_start(async_crtc, &vsync_time))
+				goto fallback;
+
 			wakeup_time = ktime_sub(vsync_time, ms_to_ktime(1));
 
 			msm_hrtimer_queue_work(&timer->work, wakeup_time,
···
 		return;
 	}
 
+fallback:
 	/*
 	 * If there is any async flush pending on updated crtcs, fold
 	 * them into the current flush.

drivers/gpu/drm/msm/msm_kms.h

···
 	void (*disable_commit)(struct msm_kms *kms);
 
 	/**
-	 * If the kms backend supports async commit, it should implement
-	 * this method to return the time of the next vsync.  This is
-	 * used to determine a time slightly before vsync, for the async
-	 * commit timer to run and complete an async commit.
-	 */
-	ktime_t (*vsync_time)(struct msm_kms *kms, struct drm_crtc *crtc);
-
-	/**
 	 * Prepare for atomic commit.  This is called after any previous
 	 * (async or otherwise) commit has completed.
 	 */