drm/ingenic: Register devm action to cleanup encoders

Since the encoders have been devm-allocated, they will be freed way
before drm_mode_config_cleanup() is called. To avoid use-after-free
conditions, we then must ensure that drm_encoder_cleanup() is called
before the encoders are freed.

v2: Use the new __drmm_simple_encoder_alloc() function

v3: Use the new drmm_plain_simple_encoder_alloc() macro

v4: Use drmm_plain_encoder_alloc() macro

Fixes: c369cb27 ("drm/ingenic: Support multiple panels/bridges")
Cc: <stable@vger.kernel.org> # 5.8+
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210327115742.18986-4-paul@crapouillou.net

drivers/gpu/drm/ingenic/ingenic-drm-drv.c

@@ -24,6 +24,7 @@
 #include <drm/drm_crtc.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_drv.h>
+#include <drm/drm_encoder.h>
 #include <drm/drm_gem_cma_helper.h>
 #include <drm/drm_fb_cma_helper.h>
 #include <drm/drm_fb_helper.h>
@@ -37,7 +38,6 @@
 #include <drm/drm_plane.h>
 #include <drm/drm_plane_helper.h>
 #include <drm/drm_probe_helper.h>
-#include <drm/drm_simple_kms_helper.h>
 #include <drm/drm_vblank.h>
 
 struct ingenic_dma_hwdesc {
@@ -1024,20 +1024,17 @@ static int ingenic_drm_bind(struct device *dev, bool has_components)
 			bridge = devm_drm_panel_bridge_add_typed(dev, panel,
 								 DRM_MODE_CONNECTOR_DPI);
 
-		encoder = devm_kzalloc(dev, sizeof(*encoder), GFP_KERNEL);
-		if (!encoder)
-			return -ENOMEM;
+		encoder = drmm_plain_encoder_alloc(drm, NULL, DRM_MODE_ENCODER_DPI, NULL);
+		if (IS_ERR(encoder)) {
+			ret = PTR_ERR(encoder);
+			dev_err(dev, "Failed to init encoder: %d\n", ret);
+			return ret;
+		}
 
 		encoder->possible_crtcs = 1;
 
 		drm_encoder_helper_add(encoder, &ingenic_drm_encoder_helper_funcs);
 
-		ret = drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_DPI);
-		if (ret) {
-			dev_err(dev, "Failed to init encoder: %d\n", ret);
-			return ret;
-		}
-
 		ret = drm_bridge_attach(encoder, bridge, NULL, 0);
 		if (ret) {
 			dev_err(dev, "Unable to attach bridge\n");