drm/ast: Move cursor pageflip into helper

The new helper ast_cursor_page_flip() switches the cursor's front and
back BOs. This simplifies the cursor plane's update helper.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200702115029.5281-6-tzimmermann@suse.de

drivers/gpu/drm/ast/ast_cursor.c

@@ -198,7 +198,7 @@ int ast_cursor_blit(struct ast_private *ast, struct drm_framebuffer *fb)
 	return ret;
 }
 
-void ast_cursor_set_base(struct ast_private *ast, u64 address)
+static void ast_cursor_set_base(struct ast_private *ast, u64 address)
 {
 	u8 addr0 = (address >> 3) & 0xff;
 	u8 addr1 = (address >> 11) & 0xff;
@@ -209,6 +209,24 @@ void ast_cursor_set_base(struct ast_private *ast, u64 address)
 	ast_set_index_reg(ast, AST_IO_CRTC_PORT, 0xca, addr2);
 }
 
+void ast_cursor_page_flip(struct ast_private *ast)
+{
+	struct drm_device *dev = ast->dev;
+	struct drm_gem_vram_object *gbo;
+	s64 off;
+
+	gbo = ast->cursor.gbo[ast->cursor.next_index];
+
+	off = drm_gem_vram_offset(gbo);
+	if (drm_WARN_ON_ONCE(dev, off < 0))
+		return; /* Bug: we didn't pin the cursor HW BO to VRAM. */
+
+	ast_cursor_set_base(ast, off);
+
+	++ast->cursor.next_index;
+	ast->cursor.next_index %= ARRAY_SIZE(ast->cursor.gbo);
+}
+
 int ast_cursor_move(struct drm_crtc *crtc, int x, int y)
 {
 	struct ast_crtc *ast_crtc = to_ast_crtc(crtc);

drivers/gpu/drm/ast/ast_drv.h

@@ -319,7 +319,7 @@ void ast_release_firmware(struct drm_device *dev);
 int ast_cursor_init(struct ast_private *ast);
 void ast_cursor_fini(struct ast_private *ast);
 int ast_cursor_blit(struct ast_private *ast, struct drm_framebuffer *fb);
-void ast_cursor_set_base(struct ast_private *ast, u64 address);
+void ast_cursor_page_flip(struct ast_private *ast);
 int ast_cursor_move(struct drm_crtc *crtc, int x, int y);
 
 #endif

drivers/gpu/drm/ast/ast_mode.c

@@ -660,14 +660,11 @@ static void
 ast_cursor_plane_helper_atomic_update(struct drm_plane *plane,
 				      struct drm_plane_state *old_state)
 {
-	struct drm_device *dev = plane->dev;
 	struct drm_plane_state *state = plane->state;
 	struct drm_crtc *crtc = state->crtc;
 	struct drm_framebuffer *fb = state->fb;
 	struct ast_private *ast = to_ast_private(plane->dev);
 	struct ast_crtc *ast_crtc = to_ast_crtc(crtc);
-	struct drm_gem_vram_object *gbo;
-	s64 off;
 	u8 jreg;
 
 	ast_crtc->offset_x = AST_MAX_HWC_WIDTH - fb->width;
@@ -675,14 +672,7 @@ ast_cursor_plane_helper_atomic_update(struct drm_plane *plane,
 
 	if (state->fb != old_state->fb) {
 		/* A new cursor image was installed. */
-		gbo = ast->cursor.gbo[ast->cursor.next_index];
+		ast_cursor_page_flip(ast);
-		off = drm_gem_vram_offset(gbo);
-		if (drm_WARN_ON_ONCE(dev, off < 0))
-			return; /* Bug: we didn't pin cursor HW BO to VRAM. */
-		ast_cursor_set_base(ast, off);
-
-		++ast->cursor.next_index;
-		ast->cursor.next_index %= ARRAY_SIZE(ast->cursor.gbo);
 	}
 
 	ast_cursor_move(crtc, state->crtc_x, state->crtc_y);