Hi Hans,
On Mon, Sep 04, 2017 at 04:56:29PM +0200, Hans Verkuil wrote:
> On 09/03/2017 07:49 PM, Sakari Ailus wrote:
> > Registering a notifier has required the knowledge of struct v4l2_device
> > for the reason that sub-devices generally are registered to the
> > v4l2_device (as well as the media device, also available through
> > v4l2_device).
> >
> > This information is not available for sub-device drivers at probe time.
> >
> > What this patch does is that it allows registering notifiers without
> > having v4l2_device around. Instead the sub-device pointer is stored to the
> > notifier. Once the sub-device of the driver that registered the notifier
> > is registered, the notifier will gain the knowledge of the v4l2_device,
> > and the binding of async sub-devices from the sub-device driver's notifier
> > may proceed.
> >
> > The master notifier's complete callback is only called when all sub-device
> > notifiers are completed.
> >
> > Signed-off-by: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > ---
> > drivers/media/v4l2-core/v4l2-async.c | 153 +++++++++++++++++++++++++++++------
> > include/media/v4l2-async.h | 19 ++++-
> > 2 files changed, 146 insertions(+), 26 deletions(-)
> >
> > diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
> > index 70d02378b48f..55d7886103d2 100644
> > --- a/drivers/media/v4l2-core/v4l2-async.c
> > +++ b/drivers/media/v4l2-core/v4l2-async.c
> > @@ -25,6 +25,10 @@
> > #include <media/v4l2-fwnode.h>
> > #include <media/v4l2-subdev.h>
> >
> > +static int v4l2_async_test_notify(struct v4l2_async_notifier *notifier,
> > + struct v4l2_subdev *sd,
> > + struct v4l2_async_subdev *asd);
> > +
> > static bool match_i2c(struct v4l2_subdev *sd, struct v4l2_async_subdev *asd)
> > {
> > #if IS_ENABLED(CONFIG_I2C)
> > @@ -101,14 +105,69 @@ static struct v4l2_async_subdev *v4l2_async_belongs(struct v4l2_async_notifier *
> > return NULL;
> > }
> >
> > +static bool v4l2_async_subdev_notifiers_complete(
> > + struct v4l2_async_notifier *notifier)
> > +{
> > + struct v4l2_async_notifier *n;
> > +
> > + list_for_each_entry(n, ¬ifier->notifiers, notifiers) {
> > + if (!n->master)
> > + return false;
> > + }
> > +
> > + return true;
> > +}
> > +
> > +#define notifier_v4l2_dev(n) \
> > + (!!(n)->v4l2_dev ? (n)->v4l2_dev : \
> > + !!(n)->master ? (n)->master->v4l2_dev : NULL)
>
> Why '!!'?
I've since replaced this by a function.
My understanding is GCC 7 doesn't like a ? x : y construct where a is a
non-boolean. This will be effectively the same, but a boolean.
See e.g.
commit da48c948c263c9d87dfc64566b3373a858cc8aa2
Author: Arnd Bergmann <arnd@xxxxxxxx>
Date: Wed Jul 19 15:23:27 2017 -0400
media: fix warning on v4l2_subdev_call() result interpreted as bool
v4l2_subdev_call is a macro returning whatever the callback return
type is, usually 'int'. With gcc-7 and ccache, this can lead to
many wanings like:
media/platform/pxa_camera.c: In function 'pxa_mbus_build_fmts_xlate':
media/platform/pxa_camera.c:766:27: error: ?: using integer constants in boolean context [-Werror=int-in-bool-context]
while (!v4l2_subdev_call(subdev, pad, enum_mbus_code, NULL, &code)) {
media/atomisp/pci/atomisp2/atomisp_cmd.c: In function 'atomisp_s_ae_window':
media/atomisp/pci/atomisp2/atomisp_cmd.c:6414:52: error: ?: using integer constants in boolean context [-Werror=int-in-bool-context]
if (v4l2_subdev_call(isp->inputs[asd->input_curr].camera,
The problem here is that after preprocessing, we the compiler
sees a variation of
if (a ? 0 : 2)
that it thinks is suspicious.
This replaces the ?: operator with an different expression that
does the same thing in a more easily readable way that cannot
tigger the warning
Link: https://lkml.org/lkml/2017/7/14/156
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxxxxx>
>
> > +
> > +static struct v4l2_async_notifier *v4l2_async_get_subdev_notifier(
> > + struct v4l2_async_notifier *notifier, struct v4l2_subdev *sd)
> > +{
> > + struct v4l2_async_notifier *n;
> > +
> > + list_for_each_entry(n, ¬ifier_list, list) {
> > + if (n->sd == sd)
> > + return n;
> > + }
> > +
> > + return NULL;
> > +}
> > +
> > +static int v4l2_async_notifier_test_all_subdevs(
> > + struct v4l2_async_notifier *notifier)
> > +{
> > + struct v4l2_subdev *sd, *tmp;
> > +
> > + if (!notifier_v4l2_dev(notifier))
> > + return 0;
> > +
> > + list_for_each_entry_safe(sd, tmp, &subdev_list, async_list) {
> > + struct v4l2_async_subdev *asd;
> > + int ret;
> > +
> > + asd = v4l2_async_belongs(notifier, sd);
> > + if (!asd)
> > + continue;
> > +
> > + ret = v4l2_async_test_notify(notifier, sd, asd);
> > + if (ret < 0)
> > + return ret;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > static int v4l2_async_test_notify(struct v4l2_async_notifier *notifier,
> > struct v4l2_subdev *sd,
> > struct v4l2_async_subdev *asd)
>
> A general note (not specific to this patch series): I really don't like
> this function name. v4l2_async_match_notify is a much better name.
>
> With 'test' I get association with 'testing something' and not that it is
> a match.
>
> I have a similar problem with v4l2_async_belongs: v4l2_async_find_match
> makes a lot more sense.
I can prepend the set with a patch renaming them.
>
> > {
> > + struct v4l2_async_notifier *subdev_notifier;
> > int ret;
> >
> > - ret = v4l2_device_register_subdev(notifier->v4l2_dev, sd);
> > - if (ret < 0)
> > + ret = v4l2_device_register_subdev(notifier_v4l2_dev(notifier), sd);
> > + if (ret)
> > return ret;
> >
> > ret = v4l2_async_notifier_call_int_op(notifier, bound, sd, asd);
> > @@ -125,8 +184,26 @@ static int v4l2_async_test_notify(struct v4l2_async_notifier *notifier,
> > /* Move from the global subdevice list to notifier's done */
> > list_move(&sd->async_list, ¬ifier->done);
> >
> > - if (list_empty(¬ifier->waiting) && notifier->ops->complete)
> > - return v4l2_async_notifier_call_int_op(notifier, complete);
> > + subdev_notifier = v4l2_async_get_subdev_notifier(notifier, sd);
> > + if (subdev_notifier && !subdev_notifier->master) {
> > + subdev_notifier->master = notifier;
> > + list_add(&subdev_notifier->notifiers, ¬ifier->notifiers);
> > + ret = v4l2_async_notifier_test_all_subdevs(subdev_notifier);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + if (list_empty(¬ifier->waiting) &&
> > + v4l2_async_subdev_notifiers_complete(notifier)) {
> > + ret = v4l2_async_notifier_call_int_op(notifier, complete);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + if (notifier->master && list_empty(¬ifier->master->waiting) &&
> > + v4l2_async_subdev_notifiers_complete(notifier->master))
> > + return v4l2_async_notifier_call_int_op(notifier->master,
> > + complete);
> >
> > return 0;
> > }
> > @@ -140,18 +217,17 @@ static void v4l2_async_cleanup(struct v4l2_subdev *sd)
> > sd->dev = NULL;
> > }
> >
> > -int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> > - struct v4l2_async_notifier *notifier)
> > +static int __v4l2_async_notifier_register(struct v4l2_async_notifier *notifier)
> > {
> > - struct v4l2_subdev *sd, *tmp;
> > struct v4l2_async_subdev *asd;
> > + int ret;
> > int i;
> >
> > - if (!v4l2_dev || !notifier->num_subdevs ||
> > + if (!!notifier->v4l2_dev == !!notifier->sd || !notifier->num_subdevs ||
>
> '!!notifier->v4l2_dev == !!notifier->sd'???
>
> This is '(notifier->v4l2_dev && notifier->sd) || (!notifier->v4l2_dev && !notifier->sd)'
> but it took me a bit of time to parse that.
>
> A 10 for creativity, but not so much for readability :-)
:-D
>
> I suspect it can be simplified as well, or some of these tests can be moved to
> the two functions that call this one. I think that might be best, in fact.
A single ! would be actually enough. What would you think of that? A bit
less too loud? :-) It should be easies to grasp: both cannot be NULL or
non-NULL.
I've moved the check for v4l2_dev or sd to the appropriate functions. Still
it could be worth checking for this just in case.
>
> > notifier->num_subdevs > V4L2_MAX_SUBDEVS)
> > return -EINVAL;
> >
> > - notifier->v4l2_dev = v4l2_dev;
> > + INIT_LIST_HEAD(¬ifier->notifiers);
> > INIT_LIST_HEAD(¬ifier->waiting);
> > INIT_LIST_HEAD(¬ifier->done);
> >
> > @@ -175,18 +251,10 @@ int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> >
> > mutex_lock(&list_lock);
> >
> > - list_for_each_entry_safe(sd, tmp, &subdev_list, async_list) {
> > - int ret;
> > -
> > - asd = v4l2_async_belongs(notifier, sd);
> > - if (!asd)
> > - continue;
> > -
> > - ret = v4l2_async_test_notify(notifier, sd, asd);
> > - if (ret < 0) {
> > - mutex_unlock(&list_lock);
> > - return ret;
> > - }
> > + ret = v4l2_async_notifier_test_all_subdevs(notifier);
> > + if (ret) {
> > + mutex_unlock(&list_lock);
> > + return ret;
> > }
> >
> > /* Keep also completed notifiers on the list */
> > @@ -196,27 +264,62 @@ int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> >
> > return 0;
> > }
> > +
> > +int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> > + struct v4l2_async_notifier *notifier)
> > +{
> > + notifier->v4l2_dev = v4l2_dev;
> > +
> > + return __v4l2_async_notifier_register(notifier);
> > +}
> > EXPORT_SYMBOL(v4l2_async_notifier_register);
> >
> > +int v4l2_async_subdev_notifier_register(struct v4l2_subdev *sd,
> > + struct v4l2_async_notifier *notifier)
> > +{
> > + notifier->sd = sd;
> > +
> > + return __v4l2_async_notifier_register(notifier);
> > +}
> > +EXPORT_SYMBOL(v4l2_async_subdev_notifier_register);
> > +
> > void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
> > {
> > + struct v4l2_async_notifier *notifier_iter, *notifier_tmp;
> > struct v4l2_subdev *sd, *tmp;
> > unsigned int notif_n_subdev = notifier->num_subdevs;
> > unsigned int n_subdev = min(notif_n_subdev, V4L2_MAX_SUBDEVS);
> > struct device **dev;
> > int i = 0;
> >
> > - if (!notifier->v4l2_dev)
> > + if (!notifier->v4l2_dev && !notifier->sd)
> > return;
> >
> > dev = kvmalloc_array(n_subdev, sizeof(*dev), GFP_KERNEL);
> > if (!dev) {
> > - dev_err(notifier->v4l2_dev->dev,
> > + dev_err(notifier->v4l2_dev ?
> > + notifier->v4l2_dev->dev : notifier->sd->dev,
> > "Failed to allocate device cache!\n");
> > }
> >
> > mutex_lock(&list_lock);
> >
> > + if (notifier->v4l2_dev) {
> > + /* Remove all subdev notifiers from the master's list */
> > + list_for_each_entry_safe(notifier_iter, notifier_tmp,
> > + ¬ifier->notifiers, notifiers) {
> > + list_del_init(¬ifier_iter->notifiers);
> > + WARN_ON(notifier_iter->master != notifier);
> > + notifier_iter->master = NULL;
> > + }
> > + notifier->v4l2_dev = NULL;
> > + } else {
> > + /* Remove subdev notifier from the master's list */
> > + list_del_init(¬ifier->notifiers);
> > + notifier->master = NULL;
> > + notifier->sd = NULL;
> > + }
> > +
> > list_del(¬ifier->list);
> >
> > list_for_each_entry_safe(sd, tmp, ¬ifier->done, async_list) {
> > @@ -266,8 +369,6 @@ void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier)
> > }
> > kvfree(dev);
> >
> > - notifier->v4l2_dev = NULL;
> > -
> > /*
> > * Don't care about the waiting list, it is initialised and populated
> > * upon notifier registration.
> > @@ -287,6 +388,8 @@ void v4l2_async_notifier_release(struct v4l2_async_notifier *notifier)
> >
> > kvfree(notifier->subdevs);
> > notifier->subdevs = NULL;
> > +
> > + WARN_ON(!list_empty(¬ifier->notifiers));
> > }
> > EXPORT_SYMBOL_GPL(v4l2_async_notifier_release);
> >
> > diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
> > index c3e001e0d1f1..a5c123ac2873 100644
> > --- a/include/media/v4l2-async.h
> > +++ b/include/media/v4l2-async.h
> > @@ -110,7 +110,11 @@ struct v4l2_async_notifier_operations {
> > * @num_subdevs: number of subdevices used in the subdevs array
> > * @max_subdevs: number of subdevices allocated in the subdevs array
> > * @subdevs: array of pointers to subdevice descriptors
> > - * @v4l2_dev: pointer to struct v4l2_device
> > + * @v4l2_dev: v4l2_device of the master, for subdev notifiers NULL
> > + * @sd: sub-device that registered the notifier, NULL otherwise
> > + * @notifiers: list of struct v4l2_async_notifier, notifiers linked to this
> > + * notifier
> > + * @master: master notifier carrying @v4l2_dev
> > * @waiting: list of struct v4l2_async_subdev, waiting for their drivers
> > * @done: list of struct v4l2_subdev, already probed
> > * @list: member in a global list of notifiers
> > @@ -121,6 +125,9 @@ struct v4l2_async_notifier {
> > unsigned int max_subdevs;
> > struct v4l2_async_subdev **subdevs;
> > struct v4l2_device *v4l2_dev;
> > + struct v4l2_subdev *sd;
> > + struct list_head notifiers;
> > + struct v4l2_async_notifier *master;
> > struct list_head waiting;
> > struct list_head done;
> > struct list_head list;
> > @@ -136,6 +143,16 @@ int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
> > struct v4l2_async_notifier *notifier);
> >
> > /**
> > + * v4l2_async_subdev_notifier_register - registers a subdevice asynchronous
> > + * notifier for a sub-device
> > + *
> > + * @sd: pointer to &struct v4l2_subdev
> > + * @notifier: pointer to &struct v4l2_async_notifier
> > + */
> > +int v4l2_async_subdev_notifier_register(struct v4l2_subdev *sd,
> > + struct v4l2_async_notifier *notifier);
> > +
> > +/**
> > * v4l2_async_notifier_unregister - unregisters a subdevice asynchronous notifier
> > *
> > * @notifier: pointer to &struct v4l2_async_notifier
> >
>
> Do you have a git tree with this patch series? I think I need to look at this
> in the final version, not just the patch.
I'll upload the patches after making the latest changes.
--
Regards,
Sakari Ailus
e-mail: sakari.ailus@xxxxxx
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