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 <robh@xxxxxxxxxx>
>> Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
>> ---
>> 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 :)
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