drm/ast: Use simple encoder

The ast driver uses an empty implementation for its encoder. Replace
the code with the generic simple encoder.

v2:
	* rebase onto new simple-encoder interface
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200228081828.18463-3-tzimmermann@suse.de

drivers/gpu/drm/ast/ast_drv.h

@@ -121,6 +121,7 @@ struct ast_private {
 		unsigned int next_index;
 	} cursor;
 
+	struct drm_encoder encoder;
 	struct drm_plane primary_plane;
 	struct drm_plane cursor_plane;
 
@@ -238,13 +239,8 @@ struct ast_crtc {
 	u8 offset_x, offset_y;
 };
 
-struct ast_encoder {
-	struct drm_encoder base;
-};
-
 #define to_ast_crtc(x) container_of(x, struct ast_crtc, base)
 #define to_ast_connector(x) container_of(x, struct ast_connector, base)
-#define to_ast_encoder(x) container_of(x, struct ast_encoder, base)
 
 struct ast_vbios_stdtable {
 	u8 misc;

drivers/gpu/drm/ast/ast_mode.c

@@ -40,6 +40,7 @@
 #include <drm/drm_gem_vram_helper.h>
 #include <drm/drm_plane_helper.h>
 #include <drm/drm_probe_helper.h>
+#include <drm/drm_simple_kms_helper.h>
 
 #include "ast_drv.h"
 #include "ast_tables.h"
@@ -957,28 +958,18 @@ static int ast_crtc_init(struct drm_device *dev)
  * Encoder
  */
 
-static void ast_encoder_destroy(struct drm_encoder *encoder)
-{
-	drm_encoder_cleanup(encoder);
-	kfree(encoder);
-}
-
-static const struct drm_encoder_funcs ast_enc_funcs = {
-	.destroy = ast_encoder_destroy,
-};
-
 static int ast_encoder_init(struct drm_device *dev)
 {
-	struct ast_encoder *ast_encoder;
+	struct ast_private *ast = dev->dev_private;
+	struct drm_encoder *encoder = &ast->encoder;
+	int ret;
 
-	ast_encoder = kzalloc(sizeof(struct ast_encoder), GFP_KERNEL);
-	if (!ast_encoder)
-		return -ENOMEM;
+	ret = drm_simple_encoder_init(dev, encoder, DRM_MODE_ENCODER_DAC);
+	if (ret)
+		return ret;
 
-	drm_encoder_init(dev, &ast_encoder->base, &ast_enc_funcs,
-			 DRM_MODE_ENCODER_DAC, NULL);
+	encoder->possible_crtcs = 1;
 
-	ast_encoder->base.possible_crtcs = 1;
 	return 0;
 }