Hi Laurent,
On Tue, Jan 09, 2024 at 02:09:50PM +0200, Laurent Pinchart wrote:
> Hi Sakari,
>
> Thank you for the patch.
>
> On Fri, Jan 05, 2024 at 10:37:56AM +0200, Sakari Ailus wrote:
> > Add relevant debug prints for v4l2_fwnode_create_links_for_pad(). This
> > should help debugging when things go wrong.
> >
> > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Thanks!
>
> > ---
> > drivers/media/v4l2-core/v4l2-mc.c | 23 +++++++++++++++++++----
> > 1 file changed, 19 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/media/v4l2-core/v4l2-mc.c b/drivers/media/v4l2-core/v4l2-mc.c
> > index 52d349e72b8c..e394f3e505d8 100644
> > --- a/drivers/media/v4l2-core/v4l2-mc.c
> > +++ b/drivers/media/v4l2-core/v4l2-mc.c
> > @@ -337,12 +337,18 @@ int v4l2_create_fwnode_links_to_pad(struct v4l2_subdev *src_sd,
> > src_idx = media_entity_get_fwnode_pad(&src_sd->entity,
> > endpoint,
> > MEDIA_PAD_FL_SOURCE);
> > - if (src_idx < 0)
> > + if (src_idx < 0) {
> > + dev_dbg(src_sd->dev, "no pad found for %pfw\n",
>
> Make is "no source pad found", as we're looking for source pads only and
> the message would be confusing if the entity has sink pads.
I'll add this.
>
> > + endpoint);
> > continue;
> > + }
> >
> > remote_ep = fwnode_graph_get_remote_endpoint(endpoint);
> > - if (!remote_ep)
> > + if (!remote_ep) {
> > + dev_dbg(src_sd->dev, "no remote ep found for %pfw\n",
> > + endpoint);
> > continue;
> > + }
> >
> > /*
> > * ask the sink to verify it owns the remote endpoint,
> > @@ -353,8 +359,12 @@ int v4l2_create_fwnode_links_to_pad(struct v4l2_subdev *src_sd,
> > MEDIA_PAD_FL_SINK);
> > fwnode_handle_put(remote_ep);
> >
> > - if (sink_idx < 0 || sink_idx != sink->index)
> > + if (sink_idx < 0 || sink_idx != sink->index) {
> > + dev_dbg(src_sd->dev,
> > + "sink pad index mismatch or error (is %d, expected %u)\n",
> > + sink_idx, sink->index);
> > continue;
> > + }
> >
> > /*
> > * the source endpoint corresponds to one of its source pads,
> > @@ -367,8 +377,13 @@ int v4l2_create_fwnode_links_to_pad(struct v4l2_subdev *src_sd,
> > src = &src_sd->entity.pads[src_idx];
> >
> > /* skip if link already exists */
> > - if (media_entity_find_link(src, sink))
> > + if (media_entity_find_link(src, sink)) {
> > + dev_dbg(src_sd->dev,
> > + "link %s:%d -> %s:%d already exists\n",
> > + src_sd->entity.name, src_idx,
>
> Is this worth a debug message ? If the link already exists, do you
> expect this to cause any kind of issue that someone will want to debug ?
>
> Overall, are the new debug messages in this patch helped debugging a
> real life problem ?
They would have helped debugging development time versions of the previous
patch. :-)
Multiple people have also had issues debugging drivers depending on
matching sub-devices and creating links between them due to the complexity
of the firmware interface and the in-kernel framework. Telling what is
taking happening here is one way to address that.
If a link already exists, something is probably wrong. I didn't want to
make this an error in this patch as I didn't want to introduce a functional
change here. I think it could be made later on.
>
> > + sink->entity->name, sink_idx);
> > continue;
> > + }
> >
> > dev_dbg(src_sd->dev, "creating link %s:%d -> %s:%d\n",
> > src_sd->entity.name, src_idx,
>
--
Regards,
Sakari Ailus
