drm/rockchip: Make VOP driver optional

With upcoming VOP2 support VOP won't be the only choice anymore, so make
the VOP driver optional.

This also adds a dependency from ROCKCHIP_ANALOGIX_DP to ROCKCHIP_VOP,
because that driver currently only links and works with the VOP driver.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Tested-by: Michael Riesch <michael.riesch@wolfvision.net>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20220422072841.2206452-22-s.hauer@pengutronix.de

drivers/gpu/drm/rockchip/Kconfig

@@ -22,8 +22,16 @@ config DRM_ROCKCHIP
 
 if DRM_ROCKCHIP
 
+config ROCKCHIP_VOP
+	bool "Rockchip VOP driver"
+	default y
+	help
+	  This selects support for the VOP driver. You should enable it
+	  on older SoCs.
+
 config ROCKCHIP_ANALOGIX_DP
 	bool "Rockchip specific extensions for Analogix DP driver"
+	depends on ROCKCHIP_VOP
 	select DRM_DISPLAY_DP_HELPER
 	help
 	  This selects support for Rockchip SoC specific extensions

drivers/gpu/drm/rockchip/Makefile

@@ -4,8 +4,9 @@
 # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher.
 
 rockchipdrm-y := rockchip_drm_drv.o rockchip_drm_fb.o \
-		rockchip_drm_gem.o rockchip_drm_vop.o rockchip_vop_reg.o
+		rockchip_drm_gem.o
 
+rockchipdrm-$(CONFIG_ROCKCHIP_VOP) += rockchip_drm_vop.o rockchip_vop_reg.o
 rockchipdrm-$(CONFIG_ROCKCHIP_ANALOGIX_DP) += analogix_dp-rockchip.o
 rockchipdrm-$(CONFIG_ROCKCHIP_CDN_DP) += cdn-dp-core.o cdn-dp-reg.o
 rockchipdrm-$(CONFIG_ROCKCHIP_DW_HDMI) += dw_hdmi-rockchip.o

drivers/gpu/drm/rockchip/rockchip_drm_drv.c

@@ -481,7 +481,7 @@ static int __init rockchip_drm_init(void)
 		return -ENODEV;
 
 	num_rockchip_sub_drivers = 0;
-	ADD_ROCKCHIP_SUB_DRIVER(vop_platform_driver, CONFIG_DRM_ROCKCHIP);
+	ADD_ROCKCHIP_SUB_DRIVER(vop_platform_driver, CONFIG_ROCKCHIP_VOP);
 	ADD_ROCKCHIP_SUB_DRIVER(rockchip_lvds_driver,
 				CONFIG_ROCKCHIP_LVDS);
 	ADD_ROCKCHIP_SUB_DRIVER(rockchip_dp_driver,