drm/sun4i: tcon: Add TRI finish interrupt for vblank

The "CPU" (or Intel 8080) interface uses a different interrupt called
TRI_FINISH (most likely TRI being for trigger) to notify the end of frames,
and hence the VBLANK period.

And that interrupt to the possible VBLANK interrupts source.

Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/de6d6ad8959da77ea3a974a31a4c0c8391178748.1522835818.git-series.maxime.ripard@bootlin.com
diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index c3d92d5..5f423ed 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -201,7 +201,8 @@ void sun4i_tcon_enable_vblank(struct sun4i_tcon *tcon, bool enable)
 	DRM_DEBUG_DRIVER("%sabling VBLANK interrupt\n", enable ? "En" : "Dis");
 
 	mask = SUN4I_TCON_GINT0_VBLANK_ENABLE(0) |
-	       SUN4I_TCON_GINT0_VBLANK_ENABLE(1);
+		SUN4I_TCON_GINT0_VBLANK_ENABLE(1) |
+		SUN4I_TCON_GINT0_TCON0_TRI_FINISH_ENABLE;
 
 	if (enable)
 		val = mask;
@@ -582,7 +583,8 @@ static irqreturn_t sun4i_tcon_handler(int irq, void *private)
 	regmap_read(tcon->regs, SUN4I_TCON_GINT0_REG, &status);
 
 	if (!(status & (SUN4I_TCON_GINT0_VBLANK_INT(0) |
-			SUN4I_TCON_GINT0_VBLANK_INT(1))))
+			SUN4I_TCON_GINT0_VBLANK_INT(1) |
+			SUN4I_TCON_GINT0_TCON0_TRI_FINISH_INT)))
 		return IRQ_NONE;
 
 	drm_crtc_handle_vblank(&scrtc->crtc);
@@ -591,7 +593,8 @@ static irqreturn_t sun4i_tcon_handler(int irq, void *private)
 	/* Acknowledge the interrupt */
 	regmap_update_bits(tcon->regs, SUN4I_TCON_GINT0_REG,
 			   SUN4I_TCON_GINT0_VBLANK_INT(0) |
-			   SUN4I_TCON_GINT0_VBLANK_INT(1),
+			   SUN4I_TCON_GINT0_VBLANK_INT(1) |
+			   SUN4I_TCON_GINT0_TCON0_TRI_FINISH_INT,
 			   0);
 
 	if (engine->ops->vblank_quirk)