From: Maxime Ripard <maxime.ripard@free-electrons.com>
Date: Mon, 22 Jan 2018 10:25:20 +0100
Subject: drm/sun4i: engine: Add a VBLANK quirk callback
Git-commit: 3004f75fd4732a67ba1bd069a209957f3b3394d2
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

In some cases, the display engine needs to apply some quirks during the
VBLANK event. In the Display Engine 1.0 case for example, we can only
disable the frontend once the backend has been, which is at VBLANK.

Let's introduce a callback that can be implemented by the various engines.

Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/7c298d43aa1500196aa5d15d7a7c0f228c7a6f3c.1516613040.git-series.maxime.ripard@free-electrons.com

Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/sun4i/sun4i_tcon.c   |    4 ++++
 drivers/gpu/drm/sun4i/sunxi_engine.h |   13 +++++++++++++
 2 files changed, 17 insertions(+)

--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -546,6 +546,7 @@ static irqreturn_t sun4i_tcon_handler(in
 	struct sun4i_tcon *tcon = private;
 	struct drm_device *drm = tcon->drm;
 	struct sun4i_crtc *scrtc = tcon->crtc;
+	struct sunxi_engine *engine = scrtc->engine;
 	unsigned int status;
 
 	regmap_read(tcon->regs, SUN4I_TCON_GINT0_REG, &status);
@@ -563,6 +564,9 @@ static irqreturn_t sun4i_tcon_handler(in
 			   SUN4I_TCON_GINT0_VBLANK_INT(1),
 			   0);
 
+	if (engine->ops->vblank_quirk)
+		engine->ops->vblank_quirk(engine);
+
 	return IRQ_HANDLED;
 }
 
--- a/drivers/gpu/drm/sun4i/sunxi_engine.h
+++ b/drivers/gpu/drm/sun4i/sunxi_engine.h
@@ -85,6 +85,19 @@ struct sunxi_engine_ops {
 	 * This function is optional.
 	 */
 	void (*disable_color_correction)(struct sunxi_engine *engine);
+
+	/**
+	 * @vblank_quirk:
+	 *
+	 * This callback is used to implement engine-specific
+	 * behaviour part of the VBLANK event. It is run with all the
+	 * constraints of an interrupt (can't sleep, all local
+	 * interrupts disabled) and therefore should be as fast as
+	 * possible.
+	 *
+	 * This function is optional.
+	 */
+	void (*vblank_quirk)(struct sunxi_engine *engine);
 };
 
 /**