of: Decrement refcount of previous endpoint in of_graph_get_next_endpoint

Decrementing the reference count of the previous endpoint node allows to
use the of_graph_get_next_endpoint function in a for_each_... style macro.
All current users of this function that pass a non-NULL prev parameter
(that is, soc_camera and imx-drm) are changed to not decrement the passed
prev argument's refcount themselves.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Acked-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

7 files changed, 11 insertions, 48 deletions

diff --git a/drivers/coresight/of_coresight.c b/drivers/coresight/of_coresight.c
index c3efa418a86d..6f75e9d5b6fb 100644
--- a/drivers/coresight/of_coresight.c
+++ b/drivers/coresight/of_coresight.c
@@ -52,15 +52,6 @@ of_coresight_get_endpoint_device(struct device_node *endpoint)
                                endpoint, of_dev_node_match);
 }
 
-static struct device_node *of_get_coresight_endpoint(
-                const struct device_node *parent, struct device_node *prev)
-{
-        struct device_node *node = of_graph_get_next_endpoint(parent, prev);
-
-        of_node_put(prev);
-        return node;
-}
-
 static void of_coresight_get_ports(struct device_node *node,
                                    int *nr_inport, int *nr_outport)
 {
@@ -68,7 +59,7 @@ static void of_coresight_get_ports(struct device_node *node,
         int in = 0, out = 0;
 
         do {
-                ep = of_get_coresight_endpoint(node, ep);
+                ep = of_graph_get_next_endpoint(node, ep);
                 if (!ep)
                         break;
 
@@ -140,7 +131,7 @@ struct coresight_platform_data *of_get_coresight_platform_data(
                 /* Iterate through each port to discover topology */
                 do {
                         /* Get a handle on a port */
-                        ep = of_get_coresight_endpoint(node, ep);
+                        ep = of_graph_get_next_endpoint(node, ep);
                         if (!ep)
                                 break;
 
diff --git a/drivers/gpu/drm/imx/imx-drm-core.c b/drivers/gpu/drm/imx/imx-drm-core.c
index a002f53aab0e..84cf99f8d957 100644
--- a/drivers/gpu/drm/imx/imx-drm-core.c
+++ b/drivers/gpu/drm/imx/imx-drm-core.c
@@ -431,15 +431,6 @@ int imx_drm_encoder_parse_of(struct drm_device *drm,
 }
 EXPORT_SYMBOL_GPL(imx_drm_encoder_parse_of);
 
-static struct device_node *imx_drm_of_get_next_endpoint(
-                const struct device_node *parent, struct device_node *prev)
-{
-        struct device_node *node = of_graph_get_next_endpoint(parent, prev);
-
-        of_node_put(prev);
-        return node;
-}
-
 /*
  * @node: device tree node containing encoder input ports
  * @encoder: drm_encoder
@@ -457,7 +448,7 @@ int imx_drm_encoder_get_mux_id(struct device_node *node,
                 return -EINVAL;
 
         do {
-                ep = imx_drm_of_get_next_endpoint(node, ep);
+                ep = of_graph_get_next_endpoint(node, ep);
                 if (!ep)
                         break;
 
diff --git a/drivers/gpu/drm/rcar-du/rcar_du_kms.c b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
index cc9136e8ee9c..68dab2601bf5 100644
--- a/drivers/gpu/drm/rcar-du/rcar_du_kms.c
+++ b/drivers/gpu/drm/rcar-du/rcar_du_kms.c
@@ -206,7 +206,7 @@ static int rcar_du_encoders_init_one(struct rcar_du_device *rcdu,
         enum rcar_du_encoder_type enc_type = RCAR_DU_ENCODER_NONE;
         struct device_node *connector = NULL;
         struct device_node *encoder = NULL;
-        struct device_node *prev = NULL;
+        struct device_node *ep_node = NULL;
         struct device_node *entity_ep_node;
         struct device_node *entity;
         int ret;
@@ -225,11 +225,7 @@ static int rcar_du_encoders_init_one(struct rcar_du_device *rcdu,
         entity_ep_node = of_parse_phandle(ep->local_node, "remote-endpoint", 0);
 
         while (1) {
-                struct device_node *ep_node;
-
-                ep_node = of_graph_get_next_endpoint(entity, prev);
-                of_node_put(prev);
-                prev = ep_node;
+                ep_node = of_graph_get_next_endpoint(entity, ep_node);
 
                 if (!ep_node)
                         break;
@@ -300,7 +296,7 @@ static int rcar_du_encoders_init_one(struct rcar_du_device *rcdu,
 static int rcar_du_encoders_init(struct rcar_du_device *rcdu)
 {
         struct device_node *np = rcdu->dev->of_node;
-        struct device_node *prev = NULL;
+        struct device_node *ep_node = NULL;
         unsigned int num_encoders = 0;
 
         /*
@@ -308,15 +304,12 @@ static int rcar_du_encoders_init(struct rcar_du_device *rcdu)
          * pipeline.
          */
         while (1) {
-                struct device_node *ep_node;
                 enum rcar_du_output output;
                 struct of_endpoint ep;
                 unsigned int i;
                 int ret;
 
-                ep_node = of_graph_get_next_endpoint(np, prev);
-                of_node_put(prev);
-                prev = ep_node;
+                ep_node = of_graph_get_next_endpoint(np, ep_node);
 
                 if (ep_node == NULL)
                         break;
diff --git a/drivers/media/platform/am437x/am437x-vpfe.c b/drivers/media/platform/am437x/am437x-vpfe.c
index 56a5cb0d2152..0d07fca756fe 100644
--- a/drivers/media/platform/am437x/am437x-vpfe.c
+++ b/drivers/media/platform/am437x/am437x-vpfe.c
@@ -2504,7 +2504,6 @@ vpfe_get_pdata(struct platform_device *pdev)
                                              GFP_KERNEL);
                 pdata->asd[i]->match_type = V4L2_ASYNC_MATCH_OF;
                 pdata->asd[i]->match.of.node = rem;
-                of_node_put(endpoint);
                 of_node_put(rem);
         }
 
diff --git a/drivers/media/platform/soc_camera/soc_camera.c b/drivers/media/platform/soc_camera/soc_camera.c
index cee7b56f8404..f2a3d960b1a6 100644
--- a/drivers/media/platform/soc_camera/soc_camera.c
+++ b/drivers/media/platform/soc_camera/soc_camera.c
@@ -1694,7 +1694,6 @@ static void scan_of_host(struct soc_camera_host *ici)
                 if (!i)
                         soc_of_bind(ici, epn, ren->parent);
 
-                of_node_put(epn);
                 of_node_put(ren);
 
                 if (i) {
@@ -1702,6 +1701,8 @@ static void scan_of_host(struct soc_camera_host *ici)
                         break;
                 }
         }
+
+        of_node_put(epn);
 }
 
 #else
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 0a8aeb8523fe..05b20f1cca7b 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2086,8 +2086,7 @@ EXPORT_SYMBOL(of_graph_parse_endpoint);
  * @prev: previous endpoint node, or NULL to get first
  *
  * Return: An 'endpoint' node pointer with refcount incremented. Refcount
- * of the passed @prev node is not decremented, the caller have to use
- * of_node_put() on it when done.
+ * of the passed @prev node is decremented.
  */
 struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
                                         struct device_node *prev)
@@ -2123,12 +2122,6 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
                 if (WARN_ONCE(!port, "%s(): endpoint %s has no parent node\n",
                               __func__, prev->full_name))
                         return NULL;
-
-                /*
-                 * Avoid dropping prev node refcount to 0 when getting the next
-                 * child below.
-                 */
-                of_node_get(prev);
         }
 
         while (1) {
diff --git a/drivers/video/fbdev/omap2/dss/omapdss-boot-init.c b/drivers/video/fbdev/omap2/dss/omapdss-boot-init.c
index 42b87f95267c..8b6f6d5fdd68 100644
--- a/drivers/video/fbdev/omap2/dss/omapdss-boot-init.c
+++ b/drivers/video/fbdev/omap2/dss/omapdss-boot-init.c
@@ -164,20 +164,15 @@ static void __init omapdss_walk_device(struct device_node *node, bool root)
 
                 pn = of_graph_get_remote_port_parent(n);
 
-                if (!pn) {
-                        of_node_put(n);
+                if (!pn)
                         continue;
-                }
 
                 if (!of_device_is_available(pn) || omapdss_list_contains(pn)) {
                         of_node_put(pn);
-                        of_node_put(n);
                         continue;
                 }
 
                 omapdss_walk_device(pn, false);
-
-                of_node_put(n);
         }
 }