16.06.2020 16:56, Dmitry Osipenko пишет: > 16.06.2020 04:25, Laurent Pinchart пишет: >> On Tue, Jun 16, 2020 at 04:21:12AM +0300, Laurent Pinchart wrote: >>> Hi Dmitry, >>> >>> Thank you for the patch. >>> >>> On Sun, Jun 14, 2020 at 08:22:29PM +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 the graph. >>>> >>>> This patch adds of_graph_get_local_port() which returns pointer to a local >>>> port node, or NULL if graph isn't specified in a device-tree for a given >>>> device node. >>>> >>>> Reviewed-by: Rob Herring <[email protected]> >>>> Reviewed-by: Sam Ravnborg <[email protected]> >>>> Signed-off-by: Dmitry Osipenko <[email protected]> >>>> --- >>>> drivers/of/property.c | 32 +++++++++++++++++++++++--------- >>>> include/linux/of_graph.h | 7 +++++++ >>>> 2 files changed, 30 insertions(+), 9 deletions(-) >>>> >>>> diff --git a/drivers/of/property.c b/drivers/of/property.c >>>> index 1f2086f4e7ce..05c5f619b8bb 100644 >>>> --- a/drivers/of/property.c >>>> +++ b/drivers/of/property.c >>>> @@ -608,15 +608,7 @@ 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_local_port(parent); >>>> if (!port) { >>>> pr_err("graph: no port node found in %pOF\n", parent); >>>> return NULL; >>>> @@ -765,6 +757,28 @@ struct device_node *of_graph_get_remote_port(const >>>> struct device_node *node) >>>> } >>>> EXPORT_SYMBOL(of_graph_get_remote_port); >>>> >>>> +/** >>>> + * of_graph_get_local_port() - get 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. >>>> + */ >>>> +struct device_node *of_graph_get_local_port(const struct device_node >>>> *node) >> >> I forgot to mention that, given that there could be multiple 'port' >> nodes, this function would be better named >> of_graph_get_first_local_port(). 'first' here would refer to the nodes >> order in the device tree, which I believe may not match the port number. >> For instance, in the following case >> >> ports { >> #address-cells = <1>; >> #size-cells = <1>; >> port@1 { >> reg = <1>; >> }; >> port@0 { >> reg = <0>; >> }; >> }; >> >> the function would I believe return port@1. It may be a good idea to >> explain this in the documentation. > > Hello Laurent, > > It's correct that the port@1 will be returned in yours example. > > I'll improve the doc and the function's name in the next revision, thank > you for the suggestions! > >> Depending on how you use this >> function, if your only use case is to test for the presence of port >> nodes, it may be best to return a bool and name it of_graph_has_port() >> or something similar. >> >>>> +{ >>>> + 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; >>> >>> The implementation doesn't seem to match the documentation. If node is a >>> pointer to an endpoint, it should not have any ports child. > > Right, I'll reword the doc in v8. This function doesn't differentiate > between start / end points. It's up to a user of this function to check > whether node is endpoint or something else if needed. > > Thank you very much for the comments! >
Although, I re-read the doc comment and compared it to the wording of the other of_graph_*() functions and it's already good as-is to me because the doc explicitly says the "Return: First local port associated with local endpoint...", which is exactly what this function does. But still the function name and it's brief description could be improved. _______________________________________________ dri-devel mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/dri-devel
