drm: rcar-du: Don't leak device_link to CMM

The DU driver creates device_link instances between the DU and CMMs, but
never deletes them. Fix it by introducing a rcar_du_cmm structure to
group the CMM device and device_link, and deleting the links at cleanup
time.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Link: https://patch.msgid.link/20260323164526.2292491-5-laurent.pinchart+renesas@ideasonboard.com
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

Author: Laurent Pinchart

drivers/gpu/drm/renesas/rcar-du/rcar_du_crtc.c

@@ -513,13 +513,13 @@ static void rcar_du_cmm_setup(struct drm_crtc *crtc)
 	struct rcar_du_crtc *rcrtc = to_rcar_crtc(crtc);
 	struct rcar_cmm_config cmm_config = {};
 
-	if (!rcrtc->cmm)
+	if (!rcrtc->cmm->dev)
 		return;
 
 	if (drm_lut)
 		cmm_config.lut.table = (struct drm_color_lut *)drm_lut->data;
 
-	rcar_cmm_setup(rcrtc->cmm, &cmm_config);
+	rcar_cmm_setup(rcrtc->cmm->dev, &cmm_config);
 }
 
 /* -----------------------------------------------------------------------------
@@ -667,8 +667,8 @@ static void rcar_du_crtc_stop(struct rcar_du_crtc *rcrtc)
 	if (rcar_du_has(rcrtc->dev, RCAR_DU_FEATURE_VSP1_SOURCE))
 		rcar_du_vsp_disable(rcrtc);
 
-	if (rcrtc->cmm)
-		rcar_cmm_disable(rcrtc->cmm);
+	if (rcrtc->cmm->dev)
+		rcar_cmm_disable(rcrtc->cmm->dev);
 
 	/*
 	 * Select switch sync mode. This stops display operation and configures
@@ -726,8 +726,8 @@ static void rcar_du_crtc_atomic_enable(struct drm_crtc *crtc,
 	struct rcar_du_crtc_state *rstate = to_rcar_crtc_state(crtc->state);
 	struct rcar_du_device *rcdu = rcrtc->dev;
 
-	if (rcrtc->cmm)
-		rcar_cmm_enable(rcrtc->cmm);
+	if (rcrtc->cmm->dev)
+		rcar_cmm_enable(rcrtc->cmm->dev);
 	rcar_du_crtc_get(rcrtc);
 
 	/*
@@ -1300,8 +1300,8 @@ int rcar_du_crtc_create(struct rcar_du_group *rgrp, unsigned int swindex,
 		return ret;
 
 	/* CMM might be disabled for this CRTC. */
-	if (rcdu->cmms[swindex]) {
-		rcrtc->cmm = rcdu->cmms[swindex];
+	if (rcdu->cmms[swindex].dev) {
+		rcrtc->cmm = &rcdu->cmms[swindex];
 		rgrp->cmms_mask |= BIT(hwindex % 2);
 
 		drm_mode_crtc_set_gamma_size(crtc, CM2_LUT_SIZE);

drivers/gpu/drm/renesas/rcar-du/rcar_du_crtc.h

@@ -19,6 +19,7 @@
 
 #include <media/vsp1.h>
 
+struct rcar_du_cmm;
 struct rcar_du_group;
 struct rcar_du_vsp;
 
@@ -65,7 +66,7 @@ struct rcar_du_crtc {
 	unsigned int vblank_count;
 
 	struct rcar_du_group *group;
-	struct device *cmm;
+	struct rcar_du_cmm *cmm;
 	struct rcar_du_vsp *vsp;
 	unsigned int vsp_pipe;
 

drivers/gpu/drm/renesas/rcar-du/rcar_du_drv.h

@@ -22,6 +22,7 @@
 
 struct clk;
 struct device;
+struct device_link;
 struct drm_bridge;
 struct drm_property;
 struct rcar_du_device;
@@ -88,6 +89,11 @@ struct rcar_du_device_info {
 	unsigned int lvds_clk_mask;
 };
 
+struct rcar_du_cmm {
+	struct device *dev;
+	struct device_link *link;
+};
+
 #define RCAR_DU_MAX_CRTCS		4
 #define RCAR_DU_MAX_GROUPS		DIV_ROUND_UP(RCAR_DU_MAX_CRTCS, 2)
 #define RCAR_DU_MAX_VSPS		4
@@ -106,7 +112,7 @@ struct rcar_du_device {
 	unsigned int num_crtcs;
 
 	struct rcar_du_group groups[RCAR_DU_MAX_GROUPS];
-	struct device *cmms[RCAR_DU_MAX_CRTCS];
+	struct rcar_du_cmm cmms[RCAR_DU_MAX_CRTCS];
 	struct rcar_du_vsp vsps[RCAR_DU_MAX_VSPS];
 	struct drm_bridge *lvds[RCAR_DU_MAX_LVDS];
 	struct drm_bridge *dsi[RCAR_DU_MAX_DSI];

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

@@ -769,23 +769,23 @@ static int rcar_du_cmm_init(struct rcar_du_device *rcdu)
 	}
 
 	for (i = 0; i < cells; ++i) {
-		struct device_node *cmm __free(device_node) = NULL;
+		struct device_node *cmm_node __free(device_node) = NULL;
+		struct rcar_du_cmm *cmm = &rcdu->cmms[i];
 		struct platform_device *pdev;
-		struct device_link *link;
 		int ret;
 
-		cmm = of_parse_phandle(np, "renesas,cmms", i);
-		if (!cmm) {
+		cmm_node = of_parse_phandle(np, "renesas,cmms", i);
+		if (!cmm_node) {
 			dev_err(rcdu->dev,
 				"Failed to parse 'renesas,cmms' property\n");
 			return -EINVAL;
 		}
 
-		if (!of_device_is_available(cmm))
+		if (!of_device_is_available(cmm_node))
 			/* It's fine to have a phandle to a non-enabled CMM. */
 			continue;
 
-		pdev = of_find_device_by_node(cmm);
+		pdev = of_find_device_by_node(cmm_node);
 		if (!pdev) {
 			dev_err(rcdu->dev, "No device found for CMM%u\n", i);
 			return -EINVAL;
@@ -801,14 +801,15 @@ static int rcar_du_cmm_init(struct rcar_du_device *rcdu)
 			return ret == -ENODEV ? 0 : ret;
 		}
 
-		rcdu->cmms[i] = &pdev->dev;
+		cmm->dev = &pdev->dev;
 
 		/*
 		 * Enforce suspend/resume ordering by making the CMM a provider
 		 * of the DU: CMM is suspended after and resumed before the DU.
 		 */
-		link = device_link_add(rcdu->dev, &pdev->dev, DL_FLAG_STATELESS);
-		if (!link) {
+		cmm->link = device_link_add(rcdu->dev, cmm->dev,
+					    DL_FLAG_STATELESS);
+		if (!cmm->link) {
 			dev_err(rcdu->dev,
 				"Failed to create device link to CMM%u\n", i);
 			return -EINVAL;
@@ -823,8 +824,14 @@ 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)
-		put_device(rcdu->cmms[i]);
+	for (i = 0; i < ARRAY_SIZE(rcdu->cmms); ++i) {
+		struct rcar_du_cmm *cmm = &rcdu->cmms[i];
+
+		if (cmm->link)
+			device_link_del(cmm->link);
+
+		put_device(cmm->dev);
+	}
 }
 
 int rcar_du_modeset_init(struct rcar_du_device *rcdu)