drm: rcar-du: Fix leak of CMM platform device reference

The device references acquired by of_find_device_by_node() are not
released by the driver. Fix this by registering a cleanup action.

Fixes: 8de707ae ("drm: rcar-du: kms: Initialize CMM instances")
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>

drivers/gpu/drm/rcar-du/rcar_du_kms.c

@@ -14,6 +14,7 @@
 #include <drm/drm_fb_cma_helper.h>
 #include <drm/drm_gem_cma_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_managed.h>
 #include <drm/drm_probe_helper.h>
 #include <drm/drm_vblank.h>
 
@@ -726,8 +727,12 @@ static int rcar_du_cmm_init(struct rcar_du_device *rcdu)
 		 * disabled: return 0 and let the DU continue probing.
 		 */
 		ret = rcar_cmm_init(pdev);
-		if (ret)
+		if (ret) {
+			platform_device_put(pdev);
 			return ret == -ENODEV ? 0 : ret;
+		}
+
+		rcdu->cmms[i] = pdev;
 
 		/*
 		 * Enforce suspend/resume ordering by making the CMM a provider
@@ -739,13 +744,20 @@ static int rcar_du_cmm_init(struct rcar_du_device *rcdu)
 				"Failed to create device link to CMM%u\n", i);
 			return -EINVAL;
 		}
-
-		rcdu->cmms[i] = pdev;
 	}
 
 	return 0;
 }
 
+static void rcar_du_modeset_cleanup(struct drm_device *dev, void *res)
+{
+	struct rcar_du_device *rcdu = to_rcar_du_device(dev);
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(rcdu->cmms); ++i)
+		platform_device_put(rcdu->cmms[i]);
+}
+
 int rcar_du_modeset_init(struct rcar_du_device *rcdu)
 {
 	static const unsigned int mmio_offsets[] = {
@@ -766,6 +778,10 @@ int rcar_du_modeset_init(struct rcar_du_device *rcdu)
 	if (ret)
 		return ret;
 
+	ret = drmm_add_action(&rcdu->ddev, rcar_du_modeset_cleanup, NULL);
+	if (ret)
+		return ret;
+
 	dev->mode_config.min_width = 0;
 	dev->mode_config.min_height = 0;
 	dev->mode_config.normalize_zpos = true;