Hi!
This small series improves DRM bridges code by silencing a noisy error
coming from of-graph code for the device-trees that are missing a
display bridge graph.
graph: no port node found in ...
One example where this error happens is an older bridge-less DTB used
in conjunction with a newer kernel which has a display controller driver
that supports DRM bridges.
Changelog:
v9: - These two patches are factored out from [1] in order to ease applying
of the patches.
- The of_graph_presents() is renamed to of_graph_is_present() like it
was requested by Rob Herring in the review comment to [1].
- Added Rob's r-b.
[1] https://patchwork.ozlabs.org/project/linux-tegra/list/?series=184102
Dmitry Osipenko (2):
of_graph: add of_graph_is_present()
drm/of: Make drm_of_find_panel_or_bridge() to check graph's presence
drivers/gpu/drm/drm_of.c | 9 +++++++
drivers/of/property.c | 52 +++++++++++++++++++++++++++++++++-------
include/linux/of_graph.h | 6 +++++
3 files changed, 58 insertions(+), 9 deletions(-)
--
2.26.0
In some case, like a DRM display code for example, it's useful to silently
check whether port node exists at all in a device-tree before proceeding
with parsing of the graph.
This patch adds of_graph_is_present() which returns true if given
device-tree node contains OF graph port.
Reviewed-by: Rob Herring <[email protected]>
Signed-off-by: Dmitry Osipenko <[email protected]>
---
drivers/of/property.c | 52 +++++++++++++++++++++++++++++++++-------
include/linux/of_graph.h | 6 +++++
2 files changed, 49 insertions(+), 9 deletions(-)
diff --git a/drivers/of/property.c b/drivers/of/property.c
index 6a5760f0d6cd..e12b8b491837 100644
--- a/drivers/of/property.c
+++ b/drivers/of/property.c
@@ -29,6 +29,48 @@
#include "of_private.h"
+/**
+ * of_graph_get_first_local_port() - get first local port node
+ * @node: pointer to a local endpoint device_node
+ *
+ * Return: First local port node associated with local endpoint node linked
+ * to @node. Use of_node_put() on it when done.
+ */
+static struct device_node *
+of_graph_get_first_local_port(const struct device_node *node)
+{
+ struct device_node *ports, *port;
+
+ ports = of_get_child_by_name(node, "ports");
+ if (ports)
+ node = ports;
+
+ port = of_get_child_by_name(node, "port");
+ of_node_put(ports);
+
+ return port;
+}
+
+/**
+ * of_graph_is_present() - check graph's presence
+ * @node: pointer to a device_node checked for the graph's presence
+ *
+ * Return: True if @node has a port or ports sub-node, false otherwise.
+ */
+bool of_graph_is_present(const struct device_node *node)
+{
+ struct device_node *local;
+
+ local = of_graph_get_first_local_port(node);
+ if (!local)
+ return false;
+
+ of_node_put(local);
+
+ return true;
+}
+EXPORT_SYMBOL(of_graph_is_present);
+
/**
* of_property_count_elems_of_size - Count the number of elements in a property
*
@@ -608,15 +650,7 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
* parent port node.
*/
if (!prev) {
- struct device_node *node;
-
- node = of_get_child_by_name(parent, "ports");
- if (node)
- parent = node;
-
- port = of_get_child_by_name(parent, "port");
- of_node_put(node);
-
+ port = of_graph_get_first_local_port(parent);
if (!port) {
pr_err("graph: no port node found in %pOF\n", parent);
return NULL;
diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
index 01038a6aade0..4d7756087b6b 100644
--- a/include/linux/of_graph.h
+++ b/include/linux/of_graph.h
@@ -38,6 +38,7 @@ struct of_endpoint {
child = of_graph_get_next_endpoint(parent, child))
#ifdef CONFIG_OF
+bool of_graph_is_present(const struct device_node *node);
int of_graph_parse_endpoint(const struct device_node *node,
struct of_endpoint *endpoint);
int of_graph_get_endpoint_count(const struct device_node *np);
@@ -56,6 +57,11 @@ struct device_node *of_graph_get_remote_node(const struct device_node *node,
u32 port, u32 endpoint);
#else
+static inline bool of_graph_is_present(const struct device_node *node)
+{
+ return false;
+}
+
static inline int of_graph_parse_endpoint(const struct device_node *node,
struct of_endpoint *endpoint)
{
--
2.26.0
When graph isn't defined in a device-tree, the of_graph_get_remote_node()
prints a noisy error message, telling that port node is not found. This is
undesirable behaviour in our case because absence of a panel/bridge graph
is a valid case. Let's check the graph's presence in a device-tree before
proceeding with parsing of the graph.
Reviewed-by: Sam Ravnborg <[email protected]>
Signed-off-by: Dmitry Osipenko <[email protected]>
---
drivers/gpu/drm/drm_of.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index b50b44e76279..fdb05fbf72a0 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -246,6 +246,15 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
if (panel)
*panel = NULL;
+ /*
+ * of_graph_get_remote_node() produces a noisy error message if port
+ * node isn't found and the absence of the port is a legit case here,
+ * so at first we silently check whether graph presents in the
+ * device-tree node.
+ */
+ if (!of_graph_is_present(np))
+ return -ENODEV;
+
remote = of_graph_get_remote_node(np, port, endpoint);
if (!remote)
return -ENODEV;
--
2.26.0
Hi Dmitry,
Thank you for the patch.
On Wed, Jul 01, 2020 at 05:16:16AM +0300, Dmitry Osipenko wrote:
> In some case, like a DRM display code for example, it's useful to silently
> check whether port node exists at all in a device-tree before proceeding
> with parsing of the graph.
>
> This patch adds of_graph_is_present() which returns true if given
> device-tree node contains OF graph port.
>
> Reviewed-by: Rob Herring <[email protected]>
> Signed-off-by: Dmitry Osipenko <[email protected]>
> ---
> drivers/of/property.c | 52 +++++++++++++++++++++++++++++++++-------
> include/linux/of_graph.h | 6 +++++
> 2 files changed, 49 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/of/property.c b/drivers/of/property.c
> index 6a5760f0d6cd..e12b8b491837 100644
> --- a/drivers/of/property.c
> +++ b/drivers/of/property.c
> @@ -29,6 +29,48 @@
>
> #include "of_private.h"
>
> +/**
> + * of_graph_get_first_local_port() - get first local port node
> + * @node: pointer to a local endpoint device_node
It's not an endpoint.
> + *
> + * Return: First local port node associated with local endpoint node linked
> + * to @node. Use of_node_put() on it when done.
> + */
> +static struct device_node *
> +of_graph_get_first_local_port(const struct device_node *node)
> +{
> + struct device_node *ports, *port;
> +
> + ports = of_get_child_by_name(node, "ports");
> + if (ports)
> + node = ports;
> +
> + port = of_get_child_by_name(node, "port");
> + of_node_put(ports);
> +
> + return port;
> +}
> +
> +/**
> + * of_graph_is_present() - check graph's presence
> + * @node: pointer to a device_node checked for the graph's presence
> + *
> + * Return: True if @node has a port or ports sub-node, false otherwise.
> + */
> +bool of_graph_is_present(const struct device_node *node)
> +{
> + struct device_node *local;
> +
> + local = of_graph_get_first_local_port(node);
> + if (!local)
> + return false;
> +
> + of_node_put(local);
> +
> + return true;
> +}
> +EXPORT_SYMBOL(of_graph_is_present);
> +
> /**
> * of_property_count_elems_of_size - Count the number of elements in a property
> *
> @@ -608,15 +650,7 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
> * parent port node.
> */
> if (!prev) {
> - struct device_node *node;
> -
> - node = of_get_child_by_name(parent, "ports");
> - if (node)
> - parent = node;
> -
> - port = of_get_child_by_name(parent, "port");
> - of_node_put(node);
> -
> + port = of_graph_get_first_local_port(parent);
I think this introduces a bug below in the function, where parent is
used and is expected to point to the ports node if available. I'd leave
this part of the change out, and inline +of_graph_get_first_local_port()
in of_graph_is_present().
> if (!port) {
> pr_err("graph: no port node found in %pOF\n", parent);
> return NULL;
> diff --git a/include/linux/of_graph.h b/include/linux/of_graph.h
> index 01038a6aade0..4d7756087b6b 100644
> --- a/include/linux/of_graph.h
> +++ b/include/linux/of_graph.h
> @@ -38,6 +38,7 @@ struct of_endpoint {
> child = of_graph_get_next_endpoint(parent, child))
>
> #ifdef CONFIG_OF
> +bool of_graph_is_present(const struct device_node *node);
> int of_graph_parse_endpoint(const struct device_node *node,
> struct of_endpoint *endpoint);
> int of_graph_get_endpoint_count(const struct device_node *np);
> @@ -56,6 +57,11 @@ struct device_node *of_graph_get_remote_node(const struct device_node *node,
> u32 port, u32 endpoint);
> #else
>
> +static inline bool of_graph_is_present(const struct device_node *node)
> +{
> + return false;
> +}
> +
> static inline int of_graph_parse_endpoint(const struct device_node *node,
> struct of_endpoint *endpoint)
> {
--
Regards,
Laurent Pinchart
01.07.2020 08:45, Laurent Pinchart пишет:
> Hi Dmitry,
>
> Thank you for the patch.
>
> On Wed, Jul 01, 2020 at 05:16:16AM +0300, Dmitry Osipenko wrote:
>> In some case, like a DRM display code for example, it's useful to silently
>> check whether port node exists at all in a device-tree before proceeding
>> with parsing of the graph.
>>
>> This patch adds of_graph_is_present() which returns true if given
>> device-tree node contains OF graph port.
>>
>> Reviewed-by: Rob Herring <[email protected]>
>> Signed-off-by: Dmitry Osipenko <[email protected]>
>> ---
>> drivers/of/property.c | 52 +++++++++++++++++++++++++++++++++-------
>> include/linux/of_graph.h | 6 +++++
>> 2 files changed, 49 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/of/property.c b/drivers/of/property.c
>> index 6a5760f0d6cd..e12b8b491837 100644
>> --- a/drivers/of/property.c
>> +++ b/drivers/of/property.c
>> @@ -29,6 +29,48 @@
>>
>> #include "of_private.h"
>>
>> +/**
>> + * of_graph_get_first_local_port() - get first local port node
>> + * @node: pointer to a local endpoint device_node
>
> It's not an endpoint.
Alright, somehow I was reading this as a "device_node that contains
endpoint (of the graph)". But after re-reading twice I can see that it's
not the case.
It should be a "pointer to device_node containing graph port", just like
the of_graph_get_remote_node() says it. Thank you :)
>> + *
>> + * Return: First local port node associated with local endpoint node linked
>> + * to @node. Use of_node_put() on it when done.
>> + */
>> +static struct device_node *
>> +of_graph_get_first_local_port(const struct device_node *node)
>> +{
>> + struct device_node *ports, *port;
>> +
>> + ports = of_get_child_by_name(node, "ports");
>> + if (ports)
>> + node = ports;
>> +
>> + port = of_get_child_by_name(node, "port");
>> + of_node_put(ports);
>> +
>> + return port;
>> +}
>> +
>> +/**
>> + * of_graph_is_present() - check graph's presence
>> + * @node: pointer to a device_node checked for the graph's presence
>> + *
>> + * Return: True if @node has a port or ports sub-node, false otherwise.
>> + */
>> +bool of_graph_is_present(const struct device_node *node)
>> +{
>> + struct device_node *local;
>> +
>> + local = of_graph_get_first_local_port(node);
>> + if (!local)
>> + return false;
>> +
>> + of_node_put(local);
>> +
>> + return true;
>> +}
>> +EXPORT_SYMBOL(of_graph_is_present);
>> +
>> /**
>> * of_property_count_elems_of_size - Count the number of elements in a property
>> *
>> @@ -608,15 +650,7 @@ struct device_node *of_graph_get_next_endpoint(const struct device_node *parent,
>> * parent port node.
>> */
>> if (!prev) {
>> - struct device_node *node;
>> -
>> - node = of_get_child_by_name(parent, "ports");
>> - if (node)
>> - parent = node;
>> -
>> - port = of_get_child_by_name(parent, "port");
>> - of_node_put(node);
>> -
>> + port = of_graph_get_first_local_port(parent);
>
> I think this introduces a bug below in the function, where parent is
> used and is expected to point to the ports node if available. I'd leave
> this part of the change out, and inline +of_graph_get_first_local_port()
> in of_graph_is_present().
Good catch! I'll correct this.
Thank you for the review :)