drm/ast: Pass AST device to ast_ddc_create()

The DDC code needs the AST device. Pass it to ast_ddc_create() and
avoid an internal upcast. Improves type safety within the DDC code.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sui Jingfeng <sui.jingfeng@linux.dev>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240325200855.21150-8-tzimmermann@suse.de

drivers/gpu/drm/ast/ast_ddc.c

@@ -110,8 +110,9 @@ static void ast_ddc_release(struct drm_device *dev, void *res)
 	i2c_del_adapter(&ddc->adapter);
 }
 
-struct ast_ddc *ast_ddc_create(struct drm_device *dev)
+struct ast_ddc *ast_ddc_create(struct ast_device *ast)
 {
+	struct drm_device *dev = &ast->base;
 	struct ast_ddc *ddc;
 	struct i2c_adapter *adapter;
 	struct i2c_algo_bit_data *bit;

drivers/gpu/drm/ast/ast_ddc.h

@@ -6,6 +6,7 @@
 #include <linux/i2c.h>
 #include <linux/i2c-algo-bit.h>
 
+struct ast_device;
 struct drm_device;
 
 struct ast_ddc {
@@ -14,6 +15,6 @@ struct ast_ddc {
 	struct i2c_algo_bit_data bit;
 };
 
-struct ast_ddc *ast_ddc_create(struct drm_device *dev);
+struct ast_ddc *ast_ddc_create(struct ast_device *ast);
 
 #endif

drivers/gpu/drm/ast/ast_mode.c

@@ -1388,10 +1388,11 @@ static const struct drm_connector_funcs ast_vga_connector_funcs = {
 
 static int ast_vga_connector_init(struct drm_device *dev, struct drm_connector *connector)
 {
+	struct ast_device *ast = to_ast_device(dev);
 	struct ast_ddc *ddc;
 	int ret;
 
-	ddc = ast_ddc_create(dev);
+	ddc = ast_ddc_create(ast);
 	if (IS_ERR(ddc)) {
 		ret = PTR_ERR(ddc);
 		drm_err(dev, "failed to add DDC bus for connector; ret=%d\n", ret);
@@ -1485,10 +1486,11 @@ static const struct drm_connector_funcs ast_sil164_connector_funcs = {
 
 static int ast_sil164_connector_init(struct drm_device *dev, struct drm_connector *connector)
 {
+	struct ast_device *ast = to_ast_device(dev);
 	struct ast_ddc *ddc;
 	int ret;
 
-	ddc = ast_ddc_create(dev);
+	ddc = ast_ddc_create(ast);
 	if (IS_ERR(ddc)) {
 		ret = PTR_ERR(ddc);
 		drm_err(dev, "failed to add DDC bus for connector; ret=%d\n", ret);