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

[Daniel Scally]

Hi Sakari

On 14/12/2021 21:22, Sakari Ailus wrote:
> Hi Daniel,
>
> On Tue, Dec 14, 2021 at 04:14:21PM +0000, Daniel Scally wrote:
>> 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
> Good point.
>
> There were only one type of links before the interface links were
> introduced. Some of the documentation seems to discuss pad links whereas
> the corresponding macro name is MEDIA_LNK_FL_DATA_LINK. What the links
> really represent is flow of data.
>
> It would be good to align this, although that should probably be done in a
> different context from this patchset.
>
Ack; I'll fix the comment as you suggested for now