[PATCH v2 0/8] Add of-graph helpers to loop over endpoints and find ports by id

[PATCH v2 0/8] Add of-graph helpers to loop over endpoints and find ports by id

[Philipp Zabel]

Hi,

this series converts all existing users of of_graph_get_next_endpoint that pass
a non-NULL prev argument to the function and decrement its refcount themselves
to stop doing that. The of_node_put is moved into of_graph_get_next_endpoint
instead.
This allows to add a for_each_endpoint_of_node helper macro to loop over all
endpoints in a device tree node.
The third of patch adds a of_graph_get_port_by_id function to retrieve a port
by its known port id from the device tree.
Finally, the last three patches convert functions in drm_of.c and imx-drm-core.c
to use the for_each_endpoint_of_node macro instead of of_graph_get_next_endpoint.

Changes since v1:
 - Added a comment about the child node reference count when breaking out
   of the loop of for_each_endpoint_of_node.
 - Changed id parameter to of_graph_get_port_by_id to u32
 - Simplified of_graph_get_port_by_id as suggested by Laurent,
   making use of port id defaulting to 0 if no "reg" property is given.
 - Added Laurent's ack to drm_of_find_possible_crtcs patch

The previous version can be found here: https://lkml.org/lkml/2014/8/19/280

regards
Philipp

Philipp Zabel (8):
  [media] soc_camera: Do not decrement endpoint node refcount in the
    loop
  imx-drm: Do not decrement endpoint node refcount in the loop
  of: Decrement refcount of previous endpoint in
    of_graph_get_next_endpoint
  of: Add for_each_endpoint_of_node helper macro
  of: Add of_graph_get_port_by_id function
  drm: use for_each_endpoint_of_node macro in drm_of_find_possible_crtcs
  imx-drm: use for_each_endpoint_of_node macro in
    imx_drm_encoder_get_mux_id
  imx-drm: use for_each_endpoint_of_node macro in
    imx_drm_encoder_parse_of

 drivers/gpu/drm/drm_of.c                       |  8 ++----
 drivers/media/platform/soc_camera/soc_camera.c |  2 +-
 drivers/of/base.c                              | 35 ++++++++++++++++++++------
 drivers/staging/imx-drm/imx-drm-core.c         | 34 ++++++++-----------------
 include/linux/of_graph.h                       | 18 +++++++++++++
 5 files changed, 58 insertions(+), 39 deletions(-)

-- 
2.1.0

[PATCH v2 1/8] [media] soc_camera: Do not decrement endpoint node refcount in the loop

[Philipp Zabel]

In preparation for a following patch, stop decrementing the endpoint node
refcount in the loop. This temporarily leaks a reference to the endpoint node,
which will be fixed by having of_graph_get_next_endpoint decrement the refcount
of its prev argument instead.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 drivers/media/platform/soc_camera/soc_camera.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/platform/soc_camera/soc_camera.c b/drivers/media/platform/soc_camera/soc_camera.c
index f4308fe..f752489 100644
--- a/drivers/media/platform/soc_camera/soc_camera.c
+++ b/drivers/media/platform/soc_camera/soc_camera.c
@@ -1696,11 +1696,11 @@ 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) {
 			dev_err(dev, "multiple subdevices aren't supported yet!\n");
+			of_node_put(epn);
 			break;
 		}
 	}
-- 
2.1.0

[PATCH v2 2/8] imx-drm: Do not decrement endpoint node refcount in the loop

[Philipp Zabel]

In preparation for the following patch, stop decrementing the endpoint node
refcount in the loop. This temporarily leaks a reference to the endpoint node,
which will be fixed by having of_graph_get_next_endpoint decrement the refcount
of its prev argument instead.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 drivers/staging/imx-drm/imx-drm-core.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/staging/imx-drm/imx-drm-core.c b/drivers/staging/imx-drm/imx-drm-core.c
index 6b22106..12303b3 100644
--- a/drivers/staging/imx-drm/imx-drm-core.c
+++ b/drivers/staging/imx-drm/imx-drm-core.c
@@ -434,14 +434,6 @@ static uint32_t imx_drm_find_crtc_mask(struct imx_drm_device *imxdrm,
 	return 0;
 }
 
-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;
-}
-
 int imx_drm_encoder_parse_of(struct drm_device *drm,
 	struct drm_encoder *encoder, struct device_node *np)
 {
@@ -453,7 +445,7 @@ int imx_drm_encoder_parse_of(struct drm_device *drm,
 	for (i = 0; ; i++) {
 		u32 mask;
 
-		ep = imx_drm_of_get_next_endpoint(np, ep);
+		ep = of_graph_get_next_endpoint(np, ep);
 		if (!ep)
 			break;
 
@@ -502,7 +494,7 @@ 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;
 
-- 
2.1.0

[PATCH v2 3/8] of: Decrement refcount of previous endpoint in of_graph_get_next_endpoint

[Philipp Zabel]

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.
Prior to this patch, all current users of this function that actually pass
a non-NULL prev parameter should be changed to not decrement the passed
prev argument's refcount themselves.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 drivers/of/base.c | 9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index d8574ad..a49b5628 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2058,8 +2058,7 @@ 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)
@@ -2095,12 +2094,6 @@ 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) {
-- 
2.1.0

[PATCH v2 4/8] of: Add for_each_endpoint_of_node helper macro

[Philipp Zabel]

Note that while of_graph_get_next_endpoint decrements the reference count
of the child node passed to it, of_node_put(child) still has to be called
manually when breaking out of the loop.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
Changes since v1:
 - Added a comment about the child node reference count when breaking out
   of the loop
---
 include/linux/of_graph.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
index befef42..e43442e 100644
--- a/include/linux/of_graph.h
+++ b/include/linux/of_graph.h
@@ -26,6 +26,17 @@ struct of_endpoint {
 	const struct device_node *local_node;
 };
 
+/**
+ * for_each_endpoint_of_node - iterate over every endpoint in a device node
+ * @parent: parent device node containing ports and endpoints
+ * @child: loop variable pointing to the current endpoint node
+ *
+ * When breaking out of the loop, of_node_put(child) has to be called manually.
+ */
+#define for_each_endpoint_of_node(parent, child) \
+	for (child = of_graph_get_next_endpoint(parent, NULL); child != NULL; \
+	     child = of_graph_get_next_endpoint(parent, child))
+
 #ifdef CONFIG_OF
 int of_graph_parse_endpoint(const struct device_node *node,
 				struct of_endpoint *endpoint);
-- 
2.1.0

[PATCH v2 5/8] of: Add of_graph_get_port_by_id function

[Philipp Zabel]

This patch adds a function to get a port device tree node by port id,
or reg property value.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
Changes since v1:
 - Fixed whitespace in comment
 - Changed id parameter to of_graph_get_port_by_id to u32
 - Simplified of_graph_get_port_by_id as suggested by Laurent,
   making use of port id defaulting to 0 if no "reg" property is given.
---
 drivers/of/base.c        | 26 ++++++++++++++++++++++++++
 include/linux/of_graph.h |  7 +++++++
 2 files changed, 33 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index a49b5628..b282474 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2053,6 +2053,32 @@ int of_graph_parse_endpoint(const struct device_node *node,
 EXPORT_SYMBOL(of_graph_parse_endpoint);
 
 /**
+ * of_graph_get_port_by_id() - get the port matching a given id
+ * @parent: pointer to the parent device node
+ * @id: id of the port
+ *
+ * Return: A 'port' node pointer with refcount incremented. The caller
+ * has to use of_node_put() on it when done.
+ */
+struct device_node *of_graph_get_port_by_id(struct device_node *node, u32 id)
+{
+	struct device_node *port = NULL;
+	u32 port_id = 0;
+
+	while (true) {
+		port = of_get_next_child(node, port);
+		if (!port)
+			return NULL;
+		if (of_node_cmp(port->name, "port") != 0)
+			continue;
+		of_property_read_u32(port, "reg", &port_id);
+		if (id == port_id)
+			return port;
+	}
+}
+EXPORT_SYMBOL(of_graph_get_port_by_id);
+
+/**
  * of_graph_get_next_endpoint() - get next endpoint node
  * @parent: pointer to the parent device node
  * @prev: previous endpoint node, or NULL to get first
diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
index e43442e..e028e49 100644
--- a/include/linux/of_graph.h
+++ b/include/linux/of_graph.h
@@ -40,6 +40,7 @@ struct of_endpoint {
 #ifdef CONFIG_OF
 int of_graph_parse_endpoint(const struct device_node *node,
 				struct of_endpoint *endpoint);
+struct device_node *of_graph_get_port_by_id(struct device_node *node, u32 id);
 struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
 					struct device_node *previous);
 struct device_node *of_graph_get_remote_port_parent(
@@ -53,6 +54,12 @@ static inline int of_graph_parse_endpoint(const struct device_node *node,
 	return -ENOSYS;
 }
 
+static inline struct device_node *of_graph_get_port_by_id(
+					struct device_node *node, int id)
+{
+	return NULL;
+}
+
 static inline struct device_node *of_graph_get_next_endpoint(
 					const struct device_node *parent,
 					struct device_node *previous)
-- 
2.1.0

[PATCH v2 6/8] drm: use for_each_endpoint_of_node macro in drm_of_find_possible_crtcs

[Philipp Zabel]

Using the for_each_... macro should make the code a bit shorter and
easier to read.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/gpu/drm/drm_of.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index 16150a0..024fa77 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -46,11 +46,7 @@ uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
 	struct device_node *remote_port, *ep = NULL;
 	uint32_t possible_crtcs = 0;
 
-	do {
-		ep = of_graph_get_next_endpoint(port, ep);
-		if (!ep)
-			break;
-
+	for_each_endpoint_of_node(port, ep) {
 		remote_port = of_graph_get_remote_port(ep);
 		if (!remote_port) {
 			of_node_put(ep);
@@ -60,7 +56,7 @@ uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
 		possible_crtcs |= drm_crtc_port_mask(dev, remote_port);
 
 		of_node_put(remote_port);
-	} while (1);
+	}
 
 	return possible_crtcs;
 }
-- 
2.1.0

[PATCH v2 7/8] imx-drm: use for_each_endpoint_of_node macro in imx_drm_encoder_get_mux_id

[Philipp Zabel]

Using the for_each_... macro should make the code bit shorter and
easier to read. This patch also properly decrements the endpoint node
reference count before returning out of the loop.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 drivers/staging/imx-drm/imx-drm-core.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/imx-drm/imx-drm-core.c b/drivers/staging/imx-drm/imx-drm-core.c
index 12303b3..9b5222c 100644
--- a/drivers/staging/imx-drm/imx-drm-core.c
+++ b/drivers/staging/imx-drm/imx-drm-core.c
@@ -493,18 +493,15 @@ int imx_drm_encoder_get_mux_id(struct device_node *node,
 	if (!node || !imx_crtc)
 		return -EINVAL;
 
-	do {
-		ep = of_graph_get_next_endpoint(node, ep);
-		if (!ep)
-			break;
-
+	for_each_endpoint_of_node(node, ep) {
 		port = of_graph_get_remote_port(ep);
 		of_node_put(port);
 		if (port == imx_crtc->port) {
 			ret = of_graph_parse_endpoint(ep, &endpoint);
+			of_node_put(ep);
 			return ret ? ret : endpoint.port;
 		}
-	} while (ep);
+	}
 
 	return -EINVAL;
 }
-- 
2.1.0

[PATCH v2 8/8] imx-drm: use for_each_endpoint_of_node macro in imx_drm_encoder_parse_of

[Philipp Zabel]

Using the for_each_... macro should make the code bit shorter and
easier to read.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 drivers/staging/imx-drm/imx-drm-core.c | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/drivers/staging/imx-drm/imx-drm-core.c b/drivers/staging/imx-drm/imx-drm-core.c
index 9b5222c..460d785 100644
--- a/drivers/staging/imx-drm/imx-drm-core.c
+++ b/drivers/staging/imx-drm/imx-drm-core.c
@@ -438,17 +438,13 @@ int imx_drm_encoder_parse_of(struct drm_device *drm,
 	struct drm_encoder *encoder, struct device_node *np)
 {
 	struct imx_drm_device *imxdrm = drm->dev_private;
-	struct device_node *ep = NULL;
+	struct device_node *ep;
 	uint32_t crtc_mask = 0;
-	int i;
+	int i = 0;
 
-	for (i = 0; ; i++) {
+	for_each_endpoint_of_node(np, ep) {
 		u32 mask;
 
-		ep = of_graph_get_next_endpoint(np, ep);
-		if (!ep)
-			break;
-
 		mask = imx_drm_find_crtc_mask(imxdrm, ep);
 
 		/*
@@ -457,14 +453,15 @@ int imx_drm_encoder_parse_of(struct drm_device *drm,
 		 * not been registered yet.  Defer probing, and hope that
 		 * the required CRTC is added later.
 		 */
-		if (mask == 0)
+		if (mask == 0) {
+			of_node_put(ep);
 			return -EPROBE_DEFER;
+		}
 
 		crtc_mask |= mask;
+		i++;
 	}
 
-	if (ep)
-		of_node_put(ep);
 	if (i == 0)
 		return -ENOENT;
 
-- 
2.1.0

Re: [PATCH v2 3/8] of: Decrement refcount of previous endpoint in of_graph_get_next_endpoint

[Laurent Pinchart]

Hi Philipp,

Thank you for the patch.

On Wednesday 10 September 2014 12:58:23 Philipp Zabel wrote:
> 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.
> Prior to this patch, all current users of this function that actually pass
> a non-NULL prev parameter should be changed to not decrement the passed
> prev argument's refcount themselves.
> 
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  drivers/of/base.c | 9 +--------
>  1 file changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index d8574ad..a49b5628 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -2058,8 +2058,7 @@ 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)
> @@ -2095,12 +2094,6 @@ 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) {

-- 
Regards,

Laurent Pinchart

Re: [PATCH v2 4/8] of: Add for_each_endpoint_of_node helper macro

[Laurent Pinchart]

Hi Philipp,

Thank you for the patch.

On Wednesday 10 September 2014 12:58:24 Philipp Zabel wrote:
> Note that while of_graph_get_next_endpoint decrements the reference count
> of the child node passed to it, of_node_put(child) still has to be called
> manually when breaking out of the loop.
> 
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
> Changes since v1:
>  - Added a comment about the child node reference count when breaking out
>    of the loop
> ---
>  include/linux/of_graph.h | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
> index befef42..e43442e 100644
> --- a/include/linux/of_graph.h
> +++ b/include/linux/of_graph.h
> @@ -26,6 +26,17 @@ struct of_endpoint {
>  	const struct device_node *local_node;
>  };
> 
> +/**
> + * for_each_endpoint_of_node - iterate over every endpoint in a device node
> + * @parent: parent device node containing ports and endpoints
> + * @child: loop variable pointing to the current endpoint node
> + *
> + * When breaking out of the loop, of_node_put(child) has to be called
> manually. + */
> +#define for_each_endpoint_of_node(parent, child) \
> +	for (child = of_graph_get_next_endpoint(parent, NULL); child != NULL; \
> +	     child = of_graph_get_next_endpoint(parent, child))
> +
>  #ifdef CONFIG_OF
>  int of_graph_parse_endpoint(const struct device_node *node,
>  				struct of_endpoint *endpoint);

-- 
Regards,

Laurent Pinchart

Re: [PATCH v2 5/8] of: Add of_graph_get_port_by_id function

[Laurent Pinchart]

Hi Philipp,

Thank you for the patch.

On Wednesday 10 September 2014 12:58:25 Philipp Zabel wrote:
> This patch adds a function to get a port device tree node by port id,
> or reg property value.
> 
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> ---
> Changes since v1:
>  - Fixed whitespace in comment
>  - Changed id parameter to of_graph_get_port_by_id to u32
>  - Simplified of_graph_get_port_by_id as suggested by Laurent,
>    making use of port id defaulting to 0 if no "reg" property is given.
> ---
>  drivers/of/base.c        | 26 ++++++++++++++++++++++++++
>  include/linux/of_graph.h |  7 +++++++
>  2 files changed, 33 insertions(+)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index a49b5628..b282474 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -2053,6 +2053,32 @@ int of_graph_parse_endpoint(const struct device_node
> *node, EXPORT_SYMBOL(of_graph_parse_endpoint);
> 
>  /**
> + * of_graph_get_port_by_id() - get the port matching a given id
> + * @parent: pointer to the parent device node
> + * @id: id of the port
> + *
> + * Return: A 'port' node pointer with refcount incremented. The caller
> + * has to use of_node_put() on it when done.
> + */
> +struct device_node *of_graph_get_port_by_id(struct device_node *node, u32
> id) +{
> +	struct device_node *port = NULL;

No need to initialize port to NULL.

> +	u32 port_id = 0;
> +
> +	while (true) {
> +		port = of_get_next_child(node, port);
> +		if (!port)
> +			return NULL;

How about using for_each_child_of_node() ?

> +		if (of_node_cmp(port->name, "port") != 0)
> +			continue;
> +		of_property_read_u32(port, "reg", &port_id);

A port with no reg property will be treated as having the id of the previous 
port. You can fix this by moving the port_id variable declaration inside the 
loop.

> +		if (id == port_id)
> +			return port;
> +	}
> +}
> +EXPORT_SYMBOL(of_graph_get_port_by_id);
> +
> +/**
>   * of_graph_get_next_endpoint() - get next endpoint node
>   * @parent: pointer to the parent device node
>   * @prev: previous endpoint node, or NULL to get first
> diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
> index e43442e..e028e49 100644
> --- a/include/linux/of_graph.h
> +++ b/include/linux/of_graph.h
> @@ -40,6 +40,7 @@ struct of_endpoint {
>  #ifdef CONFIG_OF
>  int of_graph_parse_endpoint(const struct device_node *node,
>  				struct of_endpoint *endpoint);
> +struct device_node *of_graph_get_port_by_id(struct device_node *node, u32
> id); struct device_node *of_graph_get_next_endpoint(const struct
> device_node *parent, struct device_node *previous);
>  struct device_node *of_graph_get_remote_port_parent(
> @@ -53,6 +54,12 @@ static inline int of_graph_parse_endpoint(const struct
> device_node *node, return -ENOSYS;
>  }
> 
> +static inline struct device_node *of_graph_get_port_by_id(
> +					struct device_node *node, int id)

id should be u32 here.

> +{
> +	return NULL;
> +}
> +
>  static inline struct device_node *of_graph_get_next_endpoint(
>  					const struct device_node *parent,
>  					struct device_node *previous)

-- 
Regards,

Laurent Pinchart