drm/sun4i: abstract a engine type

As we are going to add support for the Allwinner DE2 engine in sun4i-drm
driver, we will finally have two types of display engines -- the DE1
backend and the DE2 mixer. They both do some display blending and feed
graphics data to TCON, and is part of the "Display Engine" called by
Allwinner, so I choose to call them both "engine" here.

Abstract the engine type to a new struct with an ops struct, which contains
functions that should be called outside the engine-specified code (in
TCON, CRTC or TV Encoder code).

In order to preserve bisectability, we also switch the backend and layer
code in its own module.
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

drivers/gpu/drm/sun4i/Makefile

@@ -5,9 +5,10 @@ sun4i-tcon-y += sun4i_tcon.o
 sun4i-tcon-y += sun4i_rgb.o
 sun4i-tcon-y += sun4i_dotclock.o
 sun4i-tcon-y += sun4i_crtc.o
-sun4i-tcon-y += sun4i_layer.o
+
+sun4i-backend-y += sun4i_backend.o sun4i_layer.o
 
 obj-$(CONFIG_DRM_SUN4I)		+= sun4i-drm.o sun4i-tcon.o
-obj-$(CONFIG_DRM_SUN4I)		+= sun4i_backend.o
+obj-$(CONFIG_DRM_SUN4I)		+= sun4i-backend.o
 obj-$(CONFIG_DRM_SUN4I)		+= sun6i_drc.o
 obj-$(CONFIG_DRM_SUN4I)		+= sun4i_tv.o

drivers/gpu/drm/sun4i/sun4i_backend.c

@@ -25,6 +25,8 @@
 
 #include "sun4i_backend.h"
 #include "sun4i_drv.h"
+#include "sun4i_layer.h"
+#include "sunxi_engine.h"
 
 static const u32 sunxi_rgb2yuv_coef[12] = {
 	0x00000107, 0x00000204, 0x00000064, 0x00000108,
@@ -32,41 +34,38 @@ static const u32 sunxi_rgb2yuv_coef[12] = {
 	0x000001c1, 0x00003e88, 0x00003fb8, 0x00000808
 };
 
-void sun4i_backend_apply_color_correction(struct sun4i_backend *backend)
+static void sun4i_backend_apply_color_correction(struct sunxi_engine *engine)
 {
 	int i;
 
 	DRM_DEBUG_DRIVER("Applying RGB to YUV color correction\n");
 
 	/* Set color correction */
-	regmap_write(backend->regs, SUN4I_BACKEND_OCCTL_REG,
+	regmap_write(engine->regs, SUN4I_BACKEND_OCCTL_REG,
 		     SUN4I_BACKEND_OCCTL_ENABLE);
 
 	for (i = 0; i < 12; i++)
-		regmap_write(backend->regs, SUN4I_BACKEND_OCRCOEF_REG(i),
+		regmap_write(engine->regs, SUN4I_BACKEND_OCRCOEF_REG(i),
 			     sunxi_rgb2yuv_coef[i]);
 }
-EXPORT_SYMBOL(sun4i_backend_apply_color_correction);
 
-void sun4i_backend_disable_color_correction(struct sun4i_backend *backend)
+static void sun4i_backend_disable_color_correction(struct sunxi_engine *engine)
 {
 	DRM_DEBUG_DRIVER("Disabling color correction\n");
 
 	/* Disable color correction */
-	regmap_update_bits(backend->regs, SUN4I_BACKEND_OCCTL_REG,
+	regmap_update_bits(engine->regs, SUN4I_BACKEND_OCCTL_REG,
 			   SUN4I_BACKEND_OCCTL_ENABLE, 0);
 }
-EXPORT_SYMBOL(sun4i_backend_disable_color_correction);
 
-void sun4i_backend_commit(struct sun4i_backend *backend)
+static void sun4i_backend_commit(struct sunxi_engine *engine)
 {
 	DRM_DEBUG_DRIVER("Committing changes\n");
 
-	regmap_write(backend->regs, SUN4I_BACKEND_REGBUFFCTL_REG,
+	regmap_write(engine->regs, SUN4I_BACKEND_REGBUFFCTL_REG,
 		     SUN4I_BACKEND_REGBUFFCTL_AUTOLOAD_DIS |
 		     SUN4I_BACKEND_REGBUFFCTL_LOADCTL);
 }
-EXPORT_SYMBOL(sun4i_backend_commit);
 
 void sun4i_backend_layer_enable(struct sun4i_backend *backend,
 				int layer, bool enable)
@@ -81,10 +80,9 @@ void sun4i_backend_layer_enable(struct sun4i_backend *backend,
 	else
 		val = 0;
 
-	regmap_update_bits(backend->regs, SUN4I_BACKEND_MODCTL_REG,
+	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
 			   SUN4I_BACKEND_MODCTL_LAY_EN(layer), val);
 }
-EXPORT_SYMBOL(sun4i_backend_layer_enable);
 
 static int sun4i_backend_drm_format_to_layer(struct drm_plane *plane,
 					     u32 format, u32 *mode)
@@ -144,33 +142,33 @@ int sun4i_backend_update_layer_coord(struct sun4i_backend *backend,
 	if (plane->type == DRM_PLANE_TYPE_PRIMARY) {
 		DRM_DEBUG_DRIVER("Primary layer, updating global size W: %u H: %u\n",
 				 state->crtc_w, state->crtc_h);
-		regmap_write(backend->regs, SUN4I_BACKEND_DISSIZE_REG,
+		regmap_write(backend->engine.regs, SUN4I_BACKEND_DISSIZE_REG,
 			     SUN4I_BACKEND_DISSIZE(state->crtc_w,
 						   state->crtc_h));
 	}
 
 	/* Set the line width */
 	DRM_DEBUG_DRIVER("Layer line width: %d bits\n", fb->pitches[0] * 8);
-	regmap_write(backend->regs, SUN4I_BACKEND_LAYLINEWIDTH_REG(layer),
+	regmap_write(backend->engine.regs,
+		     SUN4I_BACKEND_LAYLINEWIDTH_REG(layer),
 		     fb->pitches[0] * 8);
 
 	/* Set height and width */
 	DRM_DEBUG_DRIVER("Layer size W: %u H: %u\n",
 			 state->crtc_w, state->crtc_h);
-	regmap_write(backend->regs, SUN4I_BACKEND_LAYSIZE_REG(layer),
+	regmap_write(backend->engine.regs, SUN4I_BACKEND_LAYSIZE_REG(layer),
 		     SUN4I_BACKEND_LAYSIZE(state->crtc_w,
 					   state->crtc_h));
 
 	/* Set base coordinates */
 	DRM_DEBUG_DRIVER("Layer coordinates X: %d Y: %d\n",
 			 state->crtc_x, state->crtc_y);
-	regmap_write(backend->regs, SUN4I_BACKEND_LAYCOOR_REG(layer),
+	regmap_write(backend->engine.regs, SUN4I_BACKEND_LAYCOOR_REG(layer),
 		     SUN4I_BACKEND_LAYCOOR(state->crtc_x,
 					   state->crtc_y));
 
 	return 0;
 }
-EXPORT_SYMBOL(sun4i_backend_update_layer_coord);
 
 int sun4i_backend_update_layer_formats(struct sun4i_backend *backend,
 				       int layer, struct drm_plane *plane)
@@ -185,7 +183,7 @@ int sun4i_backend_update_layer_formats(struct sun4i_backend *backend,
 		interlaced = plane->state->crtc->state->adjusted_mode.flags
 			& DRM_MODE_FLAG_INTERLACE;
 
-	regmap_update_bits(backend->regs, SUN4I_BACKEND_MODCTL_REG,
+	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
 			   SUN4I_BACKEND_MODCTL_ITLMOD_EN,
 			   interlaced ? SUN4I_BACKEND_MODCTL_ITLMOD_EN : 0);
 
@@ -199,12 +197,12 @@ int sun4i_backend_update_layer_formats(struct sun4i_backend *backend,
 		return ret;
 	}
 
-	regmap_update_bits(backend->regs, SUN4I_BACKEND_ATTCTL_REG1(layer),
+	regmap_update_bits(backend->engine.regs,
+			   SUN4I_BACKEND_ATTCTL_REG1(layer),
 			   SUN4I_BACKEND_ATTCTL_REG1_LAY_FBFMT, val);
 
 	return 0;
 }
-EXPORT_SYMBOL(sun4i_backend_update_layer_formats);
 
 int sun4i_backend_update_layer_buffer(struct sun4i_backend *backend,
 				      int layer, struct drm_plane *plane)
@@ -232,19 +230,19 @@ int sun4i_backend_update_layer_buffer(struct sun4i_backend *backend,
 	/* Write the 32 lower bits of the address (in bits) */
 	lo_paddr = paddr << 3;
 	DRM_DEBUG_DRIVER("Setting address lower bits to 0x%x\n", lo_paddr);
-	regmap_write(backend->regs, SUN4I_BACKEND_LAYFB_L32ADD_REG(layer),
+	regmap_write(backend->engine.regs,
+		     SUN4I_BACKEND_LAYFB_L32ADD_REG(layer),
 		     lo_paddr);
 
 	/* And the upper bits */
 	hi_paddr = paddr >> 29;
 	DRM_DEBUG_DRIVER("Setting address high bits to 0x%x\n", hi_paddr);
-	regmap_update_bits(backend->regs, SUN4I_BACKEND_LAYFB_H4ADD_REG,
+	regmap_update_bits(backend->engine.regs, SUN4I_BACKEND_LAYFB_H4ADD_REG,
 			   SUN4I_BACKEND_LAYFB_H4ADD_MSK(layer),
 			   SUN4I_BACKEND_LAYFB_H4ADD(layer, hi_paddr));
 
 	return 0;
 }
-EXPORT_SYMBOL(sun4i_backend_update_layer_buffer);
 
 static int sun4i_backend_init_sat(struct device *dev) {
 	struct sun4i_backend *backend = dev_get_drvdata(dev);
@@ -330,6 +328,13 @@ static int sun4i_backend_of_get_id(struct device_node *node)
 	return ret;
 }
 
+static const struct sunxi_engine_ops sun4i_backend_engine_ops = {
+	.commit				= sun4i_backend_commit,
+	.layers_init			= sun4i_layers_init,
+	.apply_color_correction		= sun4i_backend_apply_color_correction,
+	.disable_color_correction	= sun4i_backend_disable_color_correction,
+};
+
 static struct regmap_config sun4i_backend_regmap_config = {
 	.reg_bits	= 32,
 	.val_bits	= 32,
@@ -353,21 +358,22 @@ static int sun4i_backend_bind(struct device *dev, struct device *master,
 		return -ENOMEM;
 	dev_set_drvdata(dev, backend);
 
-	backend->node = dev->of_node;
-	backend->id = sun4i_backend_of_get_id(dev->of_node);
-	if (backend->id < 0)
-		return backend->id;
+	backend->engine.node = dev->of_node;
+	backend->engine.ops = &sun4i_backend_engine_ops;
+	backend->engine.id = sun4i_backend_of_get_id(dev->of_node);
+	if (backend->engine.id < 0)
+		return backend->engine.id;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	regs = devm_ioremap_resource(dev, res);
 	if (IS_ERR(regs))
 		return PTR_ERR(regs);
 
-	backend->regs = devm_regmap_init_mmio(dev, regs,
+	backend->engine.regs = devm_regmap_init_mmio(dev, regs,
 						     &sun4i_backend_regmap_config);
-	if (IS_ERR(backend->regs)) {
+	if (IS_ERR(backend->engine.regs)) {
 		dev_err(dev, "Couldn't create the backend regmap\n");
-		return PTR_ERR(backend->regs);
+		return PTR_ERR(backend->engine.regs);
 	}
 
 	backend->reset = devm_reset_control_get(dev, NULL);
@@ -415,18 +421,18 @@ static int sun4i_backend_bind(struct device *dev, struct device *master,
 		}
 	}
 
-	list_add_tail(&backend->list, &drv->backend_list);
+	list_add_tail(&backend->engine.list, &drv->engine_list);
 
 	/* Reset the registers */
 	for (i = 0x800; i < 0x1000; i += 4)
-		regmap_write(backend->regs, i, 0);
+		regmap_write(backend->engine.regs, i, 0);
 
 	/* Disable registers autoloading */
-	regmap_write(backend->regs, SUN4I_BACKEND_REGBUFFCTL_REG,
+	regmap_write(backend->engine.regs, SUN4I_BACKEND_REGBUFFCTL_REG,
 		     SUN4I_BACKEND_REGBUFFCTL_AUTOLOAD_DIS);
 
 	/* Enable the backend */
-	regmap_write(backend->regs, SUN4I_BACKEND_MODCTL_REG,
+	regmap_write(backend->engine.regs, SUN4I_BACKEND_MODCTL_REG,
 		     SUN4I_BACKEND_MODCTL_DEBE_EN |
 		     SUN4I_BACKEND_MODCTL_START_CTL);
 
@@ -448,7 +454,7 @@ static void sun4i_backend_unbind(struct device *dev, struct device *master,
 {
 	struct sun4i_backend *backend = dev_get_drvdata(dev);
 
-	list_del(&backend->list);
+	list_del(&backend->engine.list);
 
 	if (of_device_is_compatible(dev->of_node,
 				    "allwinner,sun8i-a33-display-backend"))

drivers/gpu/drm/sun4i/sun4i_backend.h

@@ -19,6 +19,8 @@
 #include <linux/regmap.h>
 #include <linux/reset.h>
 
+#include "sunxi_engine.h"
+
 #define SUN4I_BACKEND_MODCTL_REG		0x800
 #define SUN4I_BACKEND_MODCTL_LINE_SEL			BIT(29)
 #define SUN4I_BACKEND_MODCTL_ITLMOD_EN			BIT(28)
@@ -141,8 +143,7 @@
 #define SUN4I_BACKEND_PIPE_OFF(p)		(0x5000 + (0x400 * (p)))
 
 struct sun4i_backend {
-	struct device_node	*node;
-	struct regmap		*regs;
+	struct sunxi_engine	engine;
 
 	struct reset_control	*reset;
 
@@ -152,17 +153,13 @@ struct sun4i_backend {
 
 	struct clk		*sat_clk;
 	struct reset_control	*sat_reset;
-
-	int			id;
-
-	/* Backend list management */
-	struct list_head	list;
 };
 
-void sun4i_backend_apply_color_correction(struct sun4i_backend *backend);
-void sun4i_backend_disable_color_correction(struct sun4i_backend *backend);
-
-void sun4i_backend_commit(struct sun4i_backend *backend);
+static inline struct sun4i_backend *
+engine_to_sun4i_backend(struct sunxi_engine *engine)
+{
+	return container_of(engine, struct sun4i_backend, engine);
+}
 
 void sun4i_backend_layer_enable(struct sun4i_backend *backend,
 				int layer, bool enable);

drivers/gpu/drm/sun4i/sun4i_crtc.c

@@ -25,10 +25,9 @@
 
 #include <video/videomode.h>
 
-#include "sun4i_backend.h"
 #include "sun4i_crtc.h"
 #include "sun4i_drv.h"
-#include "sun4i_layer.h"
+#include "sunxi_engine.h"
 #include "sun4i_tcon.h"
 
 static void sun4i_crtc_atomic_begin(struct drm_crtc *crtc,
@@ -56,7 +55,7 @@ static void sun4i_crtc_atomic_flush(struct drm_crtc *crtc,
 
 	DRM_DEBUG_DRIVER("Committing plane changes\n");
 
-	sun4i_backend_commit(scrtc->backend);
+	sunxi_engine_commit(scrtc->engine);
 
 	if (event) {
 		crtc->state->event = NULL;
@@ -135,7 +134,7 @@ static const struct drm_crtc_funcs sun4i_crtc_funcs = {
 };
 
 struct sun4i_crtc *sun4i_crtc_init(struct drm_device *drm,
-				   struct sun4i_backend *backend,
+				   struct sunxi_engine *engine,
 				   struct sun4i_tcon *tcon)
 {
 	struct sun4i_crtc *scrtc;
@@ -146,11 +145,11 @@ struct sun4i_crtc *sun4i_crtc_init(struct drm_device *drm,
 	scrtc = devm_kzalloc(drm->dev, sizeof(*scrtc), GFP_KERNEL);
 	if (!scrtc)
 		return ERR_PTR(-ENOMEM);
-	scrtc->backend = backend;
+	scrtc->engine = engine;
 	scrtc->tcon = tcon;
 
 	/* Create our layers */
-	planes = sun4i_layers_init(drm, scrtc);
+	planes = sunxi_engine_layers_init(drm, engine);
 	if (IS_ERR(planes)) {
 		dev_err(drm->dev, "Couldn't create the planes\n");
 		return NULL;

drivers/gpu/drm/sun4i/sun4i_crtc.h

@@ -17,7 +17,7 @@ struct sun4i_crtc {
 	struct drm_crtc			crtc;
 	struct drm_pending_vblank_event	*event;
 
-	struct sun4i_backend		*backend;
+	struct sunxi_engine		*engine;
 	struct sun4i_tcon		*tcon;
 };
 
@@ -27,7 +27,7 @@ static inline struct sun4i_crtc *drm_crtc_to_sun4i_crtc(struct drm_crtc *crtc)
 }
 
 struct sun4i_crtc *sun4i_crtc_init(struct drm_device *drm,
-				   struct sun4i_backend *backend,
+				   struct sunxi_engine *engine,
 				   struct sun4i_tcon *tcon);
 
 #endif /* _SUN4I_CRTC_H_ */

drivers/gpu/drm/sun4i/sun4i_drv.c

@@ -91,7 +91,7 @@ static int sun4i_drv_bind(struct device *dev)
 		goto free_drm;
 	}
 	drm->dev_private = drv;
-	INIT_LIST_HEAD(&drv->backend_list);
+	INIT_LIST_HEAD(&drv->engine_list);
 	INIT_LIST_HEAD(&drv->tcon_list);
 
 	ret = of_reserved_mem_device_init(dev);

drivers/gpu/drm/sun4i/sun4i_drv.h

@@ -18,7 +18,7 @@
 #include <linux/regmap.h>
 
 struct sun4i_drv {
-	struct list_head	backend_list;
+	struct list_head	engine_list;
 	struct list_head	tcon_list;
 
 	struct drm_fbdev_cma	*fbdev;

drivers/gpu/drm/sun4i/sun4i_layer.c

@@ -11,13 +11,12 @@
  */
 
 #include <drm/drm_atomic_helper.h>
-#include <drm/drm_crtc.h>
 #include <drm/drm_plane_helper.h>
 #include <drm/drmP.h>
 
 #include "sun4i_backend.h"
-#include "sun4i_crtc.h"
 #include "sun4i_layer.h"
+#include "sunxi_engine.h"
 
 struct sun4i_plane_desc {
 	       enum drm_plane_type     type;
@@ -130,10 +129,10 @@ static struct sun4i_layer *sun4i_layer_init_one(struct drm_device *drm,
 }
 
 struct drm_plane **sun4i_layers_init(struct drm_device *drm,
-				     struct sun4i_crtc *crtc)
+				     struct sunxi_engine *engine)
 {
 	struct drm_plane **planes;
-	struct sun4i_backend *backend = crtc->backend;
+	struct sun4i_backend *backend = engine_to_sun4i_backend(engine);
 	int i;
 
 	planes = devm_kcalloc(drm->dev, ARRAY_SIZE(sun4i_backend_planes) + 1,
@@ -175,7 +174,7 @@ struct drm_plane **sun4i_layers_init(struct drm_device *drm,
 
 		DRM_DEBUG_DRIVER("Assigning %s plane to pipe %d\n",
 				 i ? "overlay" : "primary", plane->pipe);
-		regmap_update_bits(backend->regs, SUN4I_BACKEND_ATTCTL_REG0(i),
+		regmap_update_bits(engine->regs, SUN4I_BACKEND_ATTCTL_REG0(i),
 				   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL_MASK,
 				   SUN4I_BACKEND_ATTCTL_REG0_LAY_PIPESEL(plane->pipe));
 

drivers/gpu/drm/sun4i/sun4i_layer.h

@@ -13,6 +13,8 @@
 #ifndef _SUN4I_LAYER_H_
 #define _SUN4I_LAYER_H_
 
+struct sunxi_engine;
+
 struct sun4i_layer {
 	struct drm_plane	plane;
 	struct sun4i_drv	*drv;
@@ -27,6 +29,6 @@ plane_to_sun4i_layer(struct drm_plane *plane)
 }
 
 struct drm_plane **sun4i_layers_init(struct drm_device *drm,
-				     struct sun4i_crtc *crtc);
+				     struct sunxi_engine *engine);
 
 #endif /* _SUN4I_LAYER_H_ */

drivers/gpu/drm/sun4i/sun4i_tcon.c

@@ -25,12 +25,12 @@
 #include <linux/regmap.h>
 #include <linux/reset.h>
 
-#include "sun4i_backend.h"
 #include "sun4i_crtc.h"
 #include "sun4i_dotclock.h"
 #include "sun4i_drv.h"
 #include "sun4i_rgb.h"
 #include "sun4i_tcon.h"
+#include "sunxi_engine.h"
 
 void sun4i_tcon_disable(struct sun4i_tcon *tcon)
 {
@@ -419,12 +419,16 @@ static int sun4i_tcon_init_regmap(struct device *dev,
  * means maintaining a large list of them. Or, since the backend is
  * registered and binded before the TCON, we can just go through the
  * list of registered backends and compare the device node.
+ *
+ * As the structures now store engines instead of backends, here this
+ * function in fact searches the corresponding engine, and the ID is
+ * requested via the get_id function of the engine.
  */
-static struct sun4i_backend *sun4i_tcon_find_backend(struct sun4i_drv *drv,
+static struct sunxi_engine *sun4i_tcon_find_engine(struct sun4i_drv *drv,
 						   struct device_node *node)
 {
 	struct device_node *port, *ep, *remote;
-	struct sun4i_backend *backend;
+	struct sunxi_engine *engine;
 
 	port = of_graph_get_port_by_id(node, 0);
 	if (!port)
@@ -435,21 +439,21 @@ static struct sun4i_backend *sun4i_tcon_find_backend(struct sun4i_drv *drv,
 		if (!remote)
 			continue;
 
-		/* does this node match any registered backends? */
-		list_for_each_entry(backend, &drv->backend_list, list) {
-			if (remote == backend->node) {
+		/* does this node match any registered engines? */
+		list_for_each_entry(engine, &drv->engine_list, list) {
+			if (remote == engine->node) {
 				of_node_put(remote);
 				of_node_put(port);
-				return backend;
+				return engine;
 			}
 		}
 
 		/* keep looking through upstream ports */
-		backend = sun4i_tcon_find_backend(drv, remote);
-		if (!IS_ERR(backend)) {
+		engine = sun4i_tcon_find_engine(drv, remote);
+		if (!IS_ERR(engine)) {
 			of_node_put(remote);
 			of_node_put(port);
-			return backend;
+			return engine;
 		}
 	}
 
@@ -461,13 +465,13 @@ static int sun4i_tcon_bind(struct device *dev, struct device *master,
 {
 	struct drm_device *drm = data;
 	struct sun4i_drv *drv = drm->dev_private;
-	struct sun4i_backend *backend;
+	struct sunxi_engine *engine;
 	struct sun4i_tcon *tcon;
 	int ret;
 
-	backend = sun4i_tcon_find_backend(drv, dev->of_node);
-	if (IS_ERR(backend)) {
-		dev_err(dev, "Couldn't find matching backend\n");
+	engine = sun4i_tcon_find_engine(drv, dev->of_node);
+	if (IS_ERR(engine)) {
+		dev_err(dev, "Couldn't find matching engine\n");
 		return -EPROBE_DEFER;
 	}
 
@@ -477,7 +481,7 @@ static int sun4i_tcon_bind(struct device *dev, struct device *master,
 	dev_set_drvdata(dev, tcon);
 	tcon->drm = drm;
 	tcon->dev = dev;
-	tcon->id = backend->id;
+	tcon->id = engine->id;
 	tcon->quirks = of_device_get_match_data(dev);
 
 	tcon->lcd_rst = devm_reset_control_get(dev, "lcd");
@@ -520,7 +524,7 @@ static int sun4i_tcon_bind(struct device *dev, struct device *master,
 		goto err_free_dotclock;
 	}
 
-	tcon->crtc = sun4i_crtc_init(drm, backend, tcon);
+	tcon->crtc = sun4i_crtc_init(drm, engine, tcon);
 	if (IS_ERR(tcon->crtc)) {
 		dev_err(dev, "Couldn't create our CRTC\n");
 		ret = PTR_ERR(tcon->crtc);

drivers/gpu/drm/sun4i/sun4i_tv.c

@@ -22,10 +22,10 @@
 #include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 
-#include "sun4i_backend.h"
 #include "sun4i_crtc.h"
 #include "sun4i_drv.h"
 #include "sun4i_tcon.h"
+#include "sunxi_engine.h"
 
 #define SUN4I_TVE_EN_REG		0x000
 #define SUN4I_TVE_EN_DAC_MAP_MASK		GENMASK(19, 4)
@@ -353,7 +353,6 @@ static void sun4i_tv_disable(struct drm_encoder *encoder)
 	struct sun4i_tv *tv = drm_encoder_to_sun4i_tv(encoder);
 	struct sun4i_crtc *crtc = drm_crtc_to_sun4i_crtc(encoder->crtc);
 	struct sun4i_tcon *tcon = crtc->tcon;
-	struct sun4i_backend *backend = crtc->backend;
 
 	DRM_DEBUG_DRIVER("Disabling the TV Output\n");
 
@@ -362,7 +361,8 @@ static void sun4i_tv_disable(struct drm_encoder *encoder)
 	regmap_update_bits(tv->regs, SUN4I_TVE_EN_REG,
 			   SUN4I_TVE_EN_ENABLE,
 			   0);
-	sun4i_backend_disable_color_correction(backend);
+
+	sunxi_engine_disable_color_correction(crtc->engine);
 }
 
 static void sun4i_tv_enable(struct drm_encoder *encoder)
@@ -370,11 +370,10 @@ static void sun4i_tv_enable(struct drm_encoder *encoder)
 	struct sun4i_tv *tv = drm_encoder_to_sun4i_tv(encoder);
 	struct sun4i_crtc *crtc = drm_crtc_to_sun4i_crtc(encoder->crtc);
 	struct sun4i_tcon *tcon = crtc->tcon;
-	struct sun4i_backend *backend = crtc->backend;
 
 	DRM_DEBUG_DRIVER("Enabling the TV Output\n");
 
-	sun4i_backend_apply_color_correction(backend);
+	sunxi_engine_apply_color_correction(crtc->engine);
 
 	regmap_update_bits(tv->regs, SUN4I_TVE_EN_REG,
 			   SUN4I_TVE_EN_ENABLE,

drivers/gpu/drm/sun4i/sunxi_engine.h

+/*
+ * Copyright (C) 2017 Icenowy Zheng <icenowy@aosc.io>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ */
+
+#ifndef _SUNXI_ENGINE_H_
+#define _SUNXI_ENGINE_H_
+
+struct drm_plane;
+struct drm_device;
+
+struct sunxi_engine;
+
+struct sunxi_engine_ops {
+	void (*commit)(struct sunxi_engine *engine);
+	struct drm_plane **(*layers_init)(struct drm_device *drm,
+					  struct sunxi_engine *engine);
+
+	void (*apply_color_correction)(struct sunxi_engine *engine);
+	void (*disable_color_correction)(struct sunxi_engine *engine);
+};
+
+/**
+ * struct sunxi_engine - the common parts of an engine for sun4i-drm driver
+ * @ops:	the operations of the engine
+ * @node:	the of device node of the engine
+ * @regs:	the regmap of the engine
+ * @id:		the id of the engine (-1 if not used)
+ */
+struct sunxi_engine {
+	const struct sunxi_engine_ops	*ops;
+
+	struct device_node		*node;
+	struct regmap			*regs;
+
+	int id;
+
+	/* Engine list management */
+	struct list_head		list;
+};
+
+/**
+ * sunxi_engine_commit() - commit all changes of the engine
+ * @engine:	pointer to the engine
+ */
+static inline void
+sunxi_engine_commit(struct sunxi_engine *engine)
+{
+	if (engine->ops && engine->ops->commit)
+		engine->ops->commit(engine);
+}
+
+/**
+ * sunxi_engine_layers_init() - Create planes (layers) for the engine
+ * @drm:	pointer to the drm_device for which planes will be created
+ * @engine:	pointer to the engine
+ */
+static inline struct drm_plane **
+sunxi_engine_layers_init(struct drm_device *drm, struct sunxi_engine *engine)
+{
+	if (engine->ops && engine->ops->layers_init)
+		return engine->ops->layers_init(drm, engine);
+	return ERR_PTR(-ENOSYS);
+}
+
+/**
+ * sunxi_engine_apply_color_correction - Apply the RGB2YUV color correction
+ * @engine:	pointer to the engine
+ *
+ * This functionality is optional for an engine, however, if the engine is
+ * intended to be used with TV Encoder, the output will be incorrect
+ * without the color correction, due to TV Encoder expects the engine to
+ * output directly YUV signal.
+ */
+static inline void
+sunxi_engine_apply_color_correction(struct sunxi_engine *engine)
+{
+	if (engine->ops && engine->ops->apply_color_correction)
+		engine->ops->apply_color_correction(engine);
+}
+
+/**
+ * sunxi_engine_disable_color_correction - Disable the color space correction
+ * @engine:	pointer to the engine
+ *
+ * This function is paired with apply_color_correction().
+ */
+static inline void
+sunxi_engine_disable_color_correction(struct sunxi_engine *engine)
+{
+	if (engine->ops && engine->ops->disable_color_correction)
+		engine->ops->disable_color_correction(engine);
+}
+#endif /* _SUNXI_ENGINE_H_ */