Hello,
On Fri, Apr 14, 2023 at 01:46:54PM +0300, Sakari Ailus wrote:
> On Thu, Apr 13, 2023 at 06:49:52PM +0200, Jacopo Mondi wrote:
> > On Thu, Mar 30, 2023 at 02:58:37PM +0300, Sakari Ailus wrote:
> > > Just add some debug prints for V4L2 async sub-device matching process.
> > > These might come useful in figuring out why things don't work as expected.
> > >
> > > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > > ---
> > > drivers/media/v4l2-core/v4l2-async.c | 59 ++++++++++++++++++++++++----
> > > 1 file changed, 52 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> > > index 008a2a3e312e..6dd426c2ca68 100644
> > > --- a/drivers/media/v4l2-core/v4l2-async.c
> > > +++ b/drivers/media/v4l2-core/v4l2-async.c
> > > @@ -75,6 +75,12 @@ static bool match_i2c(struct v4l2_async_notifier *notifier,
> > > #endif
> > > }
> > >
> > > +static struct device *notifier_dev(struct v4l2_async_notifier *notifier)
> > > +{
> > > + return notifier->sd ? notifier->sd->dev : notifier->v4l2_dev ?
> > > + notifier->v4l2_dev->dev : NULL;
Nested ?: operators can be confusing, I'd write
if (notifier->sd)
return notifier->sd->dev
if (notifier->v4l2_dev)
return notifier->v4l2_dev->dev;
return NULL;
> > > +}
> > > +
> > > static bool
> > > match_fwnode_one(struct v4l2_async_notifier *notifier,
> > > struct v4l2_subdev *sd, struct fwnode_handle *sd_fwnode,
> > > @@ -86,13 +92,18 @@ match_fwnode_one(struct v4l2_async_notifier *notifier,
> > > bool sd_fwnode_is_ep;
> > > struct device *dev;
> > >
> > > + dev_dbg(sd->dev, "async: fwnode match: need %pfw, trying %pfw\n",
"async:" is a bit too generic as a prefix. Maybe "v4l2_async:" or
"async_nf:" instead ?
> > > + sd_fwnode, asd->match.fwnode);
> > > +
> > > /*
> > > * Both the subdev and the async subdev can provide either an endpoint
> > > * fwnode or a device fwnode. Start with the simple case of direct
> > > * fwnode matching.
> > > */
> > > - if (sd_fwnode == asd->match.fwnode)
> > > + if (sd_fwnode == asd->match.fwnode) {
> > > + dev_dbg(sd->dev, "async: direct match found\n");
> > > return true;
> > > + }
> > >
> > > /*
> > > * Otherwise, check if the sd fwnode and the asd fwnode refer to an
> > > @@ -105,8 +116,10 @@ match_fwnode_one(struct v4l2_async_notifier *notifier,
> > > sd_fwnode_is_ep = fwnode_graph_is_endpoint(sd_fwnode);
> > > asd_fwnode_is_ep = fwnode_graph_is_endpoint(asd->match.fwnode);
> > >
> > > - if (sd_fwnode_is_ep == asd_fwnode_is_ep)
> > > + if (sd_fwnode_is_ep == asd_fwnode_is_ep) {
> > > + dev_dbg(sd->dev, "async: matching node types\n");
> >
> > "matching node type" is misleading as it suggests a match has been
> > found. As both sd and asd are of the same type, I would use a
> > message similar to the above
> >
> > dev_dbg(sd->dev, "async: direct match failed\n");
>
> As it seems further matching attempts will always produce more debug
> prints, I'll just drop this altogether.
I'm not sure what you mean here. Isn't it useful to have an explicit
message on failure ? I like Jacopo's proposal.
> > > return false;
> > > + }
> > >
> > > /*
> > > * The sd and asd fwnodes are of different types. Get the device fwnode
> > > @@ -120,10 +133,15 @@ match_fwnode_one(struct v4l2_async_notifier *notifier,
> > > other_fwnode = sd_fwnode;
> > > }
> > >
> > > + dev_dbg(sd->dev, "async: fwnode compat match, need %pfw, trying %pfw\n",
> > > + dev_fwnode, other_fwnode);
> > > +
> > > fwnode_handle_put(dev_fwnode);
> > >
> > > - if (dev_fwnode != other_fwnode)
> > > + if (dev_fwnode != other_fwnode) {
> > > + dev_dbg(sd->dev, "async: compat match not found\n");
> >
> > and to be more consistent: "compat match failed"
>
> I think it's in all cases either "found" or "not found" in this patch.
>
> > > return false;
> > > + }
> > >
> > > /*
> > > * We have a heterogeneous match. Retrieve the struct device of the side
> > > @@ -143,12 +161,17 @@ match_fwnode_one(struct v4l2_async_notifier *notifier,
> > > dev->driver->name);
> > > }
> > >
> > > + dev_dbg(sd->dev, "async: compat match found\n");
> > > +
> > > return true;
> > > }
> > >
> > > static bool match_fwnode(struct v4l2_async_notifier *notifier,
> > > struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
> > > {
> > > + dev_dbg(sd->dev, "async: matching for notifier %pfw, sd %pfw\n",
Maybe mentioning "fwnode" here ?
> > > + dev_fwnode(notifier_dev(notifier)), sd->fwnode);
Is there a reason to print the notifier dev as a fwnode instead of using
dev_name() ?
I'm also wondering, wouldn't it be better to use notifier_dev(notifier)
as the dev argument to dev_dbg(), and print dev_name(sd->dev) in the
format string ? That's what you're doing below.
Also, sd->fwnode is printed in match_fwnode_one(), so you could possibly
drop it from here.
> > > +
> > > if (match_fwnode_one(notifier, sd, sd->fwnode, asd))
> > > return true;
> > >
> > > @@ -156,6 +179,8 @@ static bool match_fwnode(struct v4l2_async_notifier *notifier,
> > > if (IS_ERR_OR_NULL(sd->fwnode->secondary))
> > > return false;
> > >
> > > + dev_dbg(sd->dev, "async: trying secondary fwnode match\n");
> > > +
> > > return match_fwnode_one(notifier, sd, sd->fwnode->secondary, asd);
> > > }
> > >
> > > @@ -247,16 +272,21 @@ v4l2_async_nf_can_complete(struct v4l2_async_notifier *notifier)
> > > {
> > > struct v4l2_subdev *sd;
> > >
> > > - if (!list_empty(¬ifier->waiting))
> > > + if (!list_empty(¬ifier->waiting)) {
> > > + dev_dbg(notifier_dev(notifier), "async: waiting for subdevs\n");
> > > return false;
> > > + }
> > >
> > > list_for_each_entry(sd, ¬ifier->done, async_list) {
> > > struct v4l2_async_notifier *subdev_notifier =
> > > v4l2_async_find_subdev_notifier(sd);
> > >
> > > if (subdev_notifier &&
> > > - !v4l2_async_nf_can_complete(subdev_notifier))
> > > + !v4l2_async_nf_can_complete(subdev_notifier)) {
> > > + dev_dbg(notifier_dev(notifier),
> > > + "async: cannot complete\n");
> >
> > These two will be printed out a lot of times, don't they ?
>
> That may be, if you have many async sub-devices. Perhaps these could be
> dropped --- the user will be able to find what is still pending via sysfs.
I'm fine with that. If you want to keep the message, can you print the
subdev_notifier dev in the message here ?
> > > return false;
> > > + }
> > > }
> > >
> > > return true;
> > > @@ -269,22 +299,32 @@ v4l2_async_nf_can_complete(struct v4l2_async_notifier *notifier)
> > > static int
> > > v4l2_async_nf_try_complete(struct v4l2_async_notifier *notifier)
> > > {
> > > + struct v4l2_async_notifier *__notifier = notifier;
> > > +
> > > /* Quick check whether there are still more sub-devices here. */
> > > if (!list_empty(¬ifier->waiting))
> > > return 0;
> > >
> > > + if (notifier->sd)
> > > + dev_dbg(notifier_dev(notifier), "async: trying to complete\n");
> > > +
> > > /* Check the entire notifier tree; find the root notifier first. */
> > > while (notifier->parent)
> > > notifier = notifier->parent;
> > >
> > > /* This is root if it has v4l2_dev. */
> > > - if (!notifier->v4l2_dev)
> > > + if (!notifier->v4l2_dev) {
> > > + dev_dbg(notifier_dev(__notifier),
> > > + "async: V4L2 device not available\n");
> >
> > is this a BUG() ?
>
> No. It's that we haven't got the root notifier with the V4L2 device. It
> will presumably be found later on.
>
> > > return 0;
> > > + }
> > >
> > > /* Is everything ready? */
> > > if (!v4l2_async_nf_can_complete(notifier))
> > > return 0;
> > >
> > > + dev_dbg(notifier_dev(__notifier), "async: complete\n");
> > > +
> > > return v4l2_async_nf_call_complete(notifier);
> > > }
> > >
> > > @@ -362,7 +402,12 @@ static int v4l2_async_match_notify(struct v4l2_async_notifier *notifier,
> > > */
> > > subdev_notifier->parent = notifier;
> > >
> > > - return v4l2_async_nf_try_all_subdevs(subdev_notifier);
> > > + ret = v4l2_async_nf_try_all_subdevs(subdev_notifier);
> > > +
> > > + dev_dbg(sd->dev, "async: bound to %s's notifier (ret %d)\n",
> > > + dev_name(notifier_dev(notifier)), ret);
> > > +
> > > + return ret;
> >
> > This will only be print out if there's no subnotifier as a few lines
> > above we return early. Is this intentional ?
>
> Good point. I'll move it up, this is about the sub-device itself, not its
> notifier.
>
> > > }
> > >
> > > /* Test all async sub-devices in a notifier for a match. */
--
Regards,
Laurent Pinchart
