Hi Laurent,
On Thu, Mar 21, 2024 at 07:20:32PM +0200, Laurent Pinchart wrote:
> On Wed, Mar 20, 2024 at 07:49:27AM +0000, Sakari Ailus wrote:
> > On Wed, Mar 20, 2024 at 12:17:07AM +0200, Laurent Pinchart wrote:
> > > On Thu, Mar 14, 2024 at 09:17:08AM +0200, Tomi Valkeinen wrote:
> > > > On 13/03/2024 09:24, Sakari Ailus wrote:
> > > > > Internal source pads will be used as routing endpoints in V4L2
> > > > > [GS]_ROUTING IOCTLs, to indicate that the stream begins in the entity.
> > > > > Internal source pads are pads that have both SINK and INTERNAL flags set.
> > > > >
> > > > > Also prevent creating links to pads that have been flagged as internal and
> > > > > initialising SOURCE pads with INTERNAL flag set.
> > > > >
> > > > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > > > > ---
> > > > > .../userspace-api/media/mediactl/media-types.rst | 8 ++++++++
> > > > > drivers/media/mc/mc-entity.c | 10 ++++++++--
> > > > > include/uapi/linux/media.h | 1 +
> > > > > 3 files changed, 17 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/Documentation/userspace-api/media/mediactl/media-types.rst b/Documentation/userspace-api/media/mediactl/media-types.rst
> > > > > index 6332e8395263..f55ef055bcf8 100644
> > > > > --- a/Documentation/userspace-api/media/mediactl/media-types.rst
> > > > > +++ b/Documentation/userspace-api/media/mediactl/media-types.rst
> > > > > @@ -361,6 +361,7 @@ Types and flags used to represent the media graph elements
> > > > > .. _MEDIA-PAD-FL-SINK:
> > > > > .. _MEDIA-PAD-FL-SOURCE:
> > > > > .. _MEDIA-PAD-FL-MUST-CONNECT:
> > > > > +.. _MEDIA-PAD-FL-INTERNAL:
> > > > >
> > > > > .. flat-table:: Media pad flags
> > > > > :header-rows: 0
> > > > > @@ -381,6 +382,13 @@ Types and flags used to represent the media graph elements
> > > > > enabled links even when this flag isn't set; the absence of the flag
> > > > > doesn't imply there is none.
> > > > >
> > > > > + * - ``MEDIA_PAD_FL_INTERNAL``
> > > > > + - The internal flag indicates an internal pad that has no external
> > > > > + connections. Such a pad shall not be connected with a link.
> > >
> > > I would expand this slightly, as it's the only source of documentation
> > > regarding internal pads.
> >
> > Patch 9 adds more documentation, this patch is for MC only.
>
> That's my point, it's the only source of documentation for internal
> pads from an MC point of view, so expanding the documentation would be
> good :-)
This is MC documentation, camera sensors aren't relevant in this context.
>
> > >
> > > - The internal flag indicates an internal pad that has no external
> > > connections. This can be used to model, for instance, the pixel array
> > > internal to an image sensor. As they are internal to entities,
> > > internal pads shall not be connected with links.
> >
> > I'd drop the sentence related to sensors.
>
> I'm fine with another example, or a more generic explanation, but with
> that sentence dropped, I think this will leave the reader wondering what
> an internal pad is and what it's used for.
What we could and probably have here is that the internal sink pad
indicates a source of data. That's what it really is, whether that data is
image data or something else.
So I'd change this to:
The internal flag indicates an internal pad that has no external
connections. Such a pad shall not be connected with a link. The internal
pad flag is allowed only in conjunction with the sink pad flag. Together
the two flags indicate the pad is a source of data inside the entity.
>
> > > > > +
> > > > > + The internal flag may currently be present only in a source pad where
> > > >
> > > > s/source/sink/
> > > >
> > > > Reviewed-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
> > > > > + it indicates that the :ref:``stream <media-glossary-stream>``
> > > > > + originates from within the entity.
> > > > >
> > > > > One and only one of ``MEDIA_PAD_FL_SINK`` and ``MEDIA_PAD_FL_SOURCE``
> > > > > must be set for every pad.
> > > > > diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c
> > > > > index 0e28b9a7936e..1973e9e1013e 100644
> > > > > --- a/drivers/media/mc/mc-entity.c
> > > > > +++ b/drivers/media/mc/mc-entity.c
> > > > > @@ -213,7 +213,9 @@ int media_entity_pads_init(struct media_entity *entity, u16 num_pads,
> > > > > iter->index = i++;
> > > > >
> > > > > if (hweight32(iter->flags & (MEDIA_PAD_FL_SINK |
> > > > > - MEDIA_PAD_FL_SOURCE)) != 1) {
> > > > > + MEDIA_PAD_FL_SOURCE)) != 1 ||
> > > > > + (iter->flags & MEDIA_PAD_FL_INTERNAL &&
> > > > > + !(iter->flags & MEDIA_PAD_FL_SINK))) {
> > > > > ret = -EINVAL;
> > > > > break;
> > > > > }
> > >
> > > This may become more readable written as a switch statement:
> > >
> > > const u32 pad_flags_mask = MEDIA_PAD_FL_SINK |
> > > MEDIA_PAD_FL_SOURCE |
> > > MEDIA_PAD_FL_INTERNAL;
> > >
> > > switch (iter->flags & pad_flags_mask) {
> > > case MEDIA_PAD_FL_SINK:
> > > case MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_INTERNAL:
> > > case MEDIA_PAD_FL_SOURCE:
> > > break;
> > >
> > > default:
> > > ret = -EINVAL;
> > > break;
> > > }
> > >
> > > if (ret)
> > > break;
> > >
> > > And now that I've written this, I'm not too sure anymore :-) Another
> > > option would be
> > >
> > >
> > > const u32 pad_flags = iter->flags & (MEDIA_PAD_FL_SINK |
> > > MEDIA_PAD_FL_SOURCE |
> > > MEDIA_PAD_FL_INTERNAL);
> > >
> > > if (pad_flags != MEDIA_PAD_FL_SINK &&
> > > pad_flags != MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_INTERNAL
> > > pad_flags != MEDIA_PAD_FL_SOURCE) {
> > > ret = -EINVAL;
> > > break;
> > > }
> > >
> > > Up to you.
> >
> > I'd prefer to keep it as-is since the original check is testing two
> > independent things instead of merging them: that only either SINK or SOURCE
> > is set, and then separately that if INTERNAL is set, then SINK is set, too.
> >
> > Of the two options you suggested, I prefer the latter.
>
> I prefer the latter too, and I think it's more readable than the current
> code. If we later end up having to test for more rules, we can separate
> the checks.
I can switch to the latter.
>
> > >
> > > Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> >
> > Thank you!
> >
> > > > > @@ -1112,7 +1114,8 @@ int media_get_pad_index(struct media_entity *entity, u32 pad_type,
> > > > >
> > > > > for (i = 0; i < entity->num_pads; i++) {
> > > > > if ((entity->pads[i].flags &
> > > > > - (MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_SOURCE)) != pad_type)
> > > > > + (MEDIA_PAD_FL_SINK | MEDIA_PAD_FL_SOURCE |
> > > > > + MEDIA_PAD_FL_INTERNAL)) != pad_type)
> > > > > continue;
> > > > >
> > > > > if (entity->pads[i].sig_type == sig_type)
> > > > > @@ -1142,6 +1145,9 @@ media_create_pad_link(struct media_entity *source, u16 source_pad,
> > > > > return -EINVAL;
> > > > > if (WARN_ON(!(sink->pads[sink_pad].flags & MEDIA_PAD_FL_SINK)))
> > > > > return -EINVAL;
> > > > > + if (WARN_ON(source->pads[source_pad].flags & MEDIA_PAD_FL_INTERNAL) ||
> > > > > + WARN_ON(sink->pads[sink_pad].flags & MEDIA_PAD_FL_INTERNAL))
> > > > > + return -EINVAL;
> > > > >
> > > > > link = media_add_link(&source->links);
> > > > > if (link == NULL)
> > > > > diff --git a/include/uapi/linux/media.h b/include/uapi/linux/media.h
> > > > > index 1c80b1d6bbaf..80cfd12a43fc 100644
> > > > > --- a/include/uapi/linux/media.h
> > > > > +++ b/include/uapi/linux/media.h
> > > > > @@ -208,6 +208,7 @@ struct media_entity_desc {
> > > > > #define MEDIA_PAD_FL_SINK (1U << 0)
> > > > > #define MEDIA_PAD_FL_SOURCE (1U << 1)
> > > > > #define MEDIA_PAD_FL_MUST_CONNECT (1U << 2)
> > > > > +#define MEDIA_PAD_FL_INTERNAL (1U << 3)
> > > > >
> > > > > struct media_pad_desc {
> > > > > __u32 entity; /* entity ID */
--
Regards,
Sakari Ailus
