drm/exynos/decon5433: handle vblank in vblank interrupt

vblank should be signaled to userspace after reading framebuffers not before,
signaling it in TE interrupt looks wrong. TE triggers reading framebuffers
so it is the worst moment. Tearing is not observable because hardware prevents
it, but there are frequently skipped vblank events.
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos5433_drm_decon.c

@@ -439,8 +439,6 @@ static void decon_te_irq_handler(struct exynos_drm_crtc *crtc)
 
 	if (test_and_clear_bit(BIT_WIN_UPDATED, &ctx->flags))
 		decon_set_bits(ctx, DECON_TRIGCON, TRIGCON_SWTRIGCMD, ~0);
-
-	drm_crtc_handle_vblank(&ctx->crtc->base);
 }
 
 static void decon_clear_channels(struct exynos_drm_crtc *crtc)
@@ -573,6 +571,7 @@ static irqreturn_t decon_irq_handler(int irq, void *dev_id)
 
 		/* clear */
 		writel(val, ctx->addr + DECON_VIDINTCON1);
+		drm_crtc_handle_vblank(&ctx->crtc->base);
 	}
 
 out: