[libcamera-devel] [PATCH 3/5] media: entity: Skip non-data links in graph iteration

[Daniel Scally]

Hi Sakari

On 14/12/2021 15:01, Sakari Ailus wrote:
> Hi Daniel,
>
> On Mon, Dec 13, 2021 at 11:28:47PM +0000, Daniel Scally wrote:
>> When iterating over the media graph, don't follow links that are not
>> pad-to-pad links.
>>
>> Signed-off-by: Daniel Scally <djrscally at gmail.com>
>> ---
>> Changes since the rfc:
>>
>> 	- new patch
>>
>>  drivers/media/mc/mc-entity.c | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
>> index d79eb88bc167..aeddc3f6310e 100644
>> --- a/drivers/media/mc/mc-entity.c
>> +++ b/drivers/media/mc/mc-entity.c
>> @@ -325,6 +325,14 @@ static void media_graph_walk_iter(struct media_graph *graph)
>>  
>>  	link = list_entry(link_top(graph), typeof(*link), list);
>>  
>> +	/* If the link is not a pad-to-pad link, don't follow it */
> This comment should mention data links, not pad-to-pad links.


I wondered about the terminology of this actually...since we create
those links with media_create_pad_link(), and they're called pad-to-pad
links in the documentation [1], but in other cases called data links. Do
we need to fix those other references too?



[1] https://www.kernel.org/doc/html/v5.0/media/kapi/mc-core.html#links

>
> Seems fine apart from this.
>
>> +	if ((link->flags & MEDIA_LNK_FL_LINK_TYPE) != MEDIA_LNK_FL_DATA_LINK) {
>> +		link_top(graph) = link_top(graph)->next;
>> +		dev_dbg(entity->graph_obj.mdev->dev, "walk: skipping %s link\n",
>> +			link_type(link));
>> +		return;
>> +	}
>> +
>>  	/* The link is not enabled so we do not follow. */
>>  	if (!(link->flags & MEDIA_LNK_FL_ENABLED)) {
>>  		link_top(graph) = link_top(graph)->next;