Re: [PATCH v13 14/25] v4l: async: Allow binding notifiers to sub-devices

[Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>]

Hi Sakari,

On Tuesday, 19 September 2017 18:17:32 EEST Sakari Ailus wrote:
> On Tue, Sep 19, 2017 at 04:52:29PM +0300, Laurent Pinchart wrote:
> > On Friday, 15 September 2017 17:17:13 EEST 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 in
> >> 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 root notifier's complete callback is only called when all sub-device
> >> notifiers are completed.
> > 
> > This is a bit hard to review, shouldn't it be split in two patches, one
> > that refactors the functions, and another one that allows binding
> > notifiers to subdevs ?
> > 
> >> Signed-off-by: Sakari Ailus <sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
> >> ---
> >> 
> >>  drivers/media/v4l2-core/v4l2-async.c | 218 ++++++++++++++++++++++++-----
> >>  include/media/v4l2-async.h           |  16 ++-
> >>  2 files changed, 203 insertions(+), 31 deletions(-)
> >> 
> >> diff --git a/drivers/media/v4l2-core/v4l2-async.c
> >> b/drivers/media/v4l2-core/v4l2-async.c index 4be2f16af051..52fe22b9b6b4
> >> 100644
> >> --- a/drivers/media/v4l2-core/v4l2-async.c
> >> +++ b/drivers/media/v4l2-core/v4l2-async.c

[snip]

> >> +/* Unbind all sub-devices in the notifier tree. */
> >> +static void v4l2_async_notifier_unbind_all_subdevs(
> >> +	struct v4l2_async_notifier *notifier)
> >> +{
> >> +	struct v4l2_subdev *sd, *tmp;
> >> 
> >>  	list_for_each_entry_safe(sd, tmp, &notifier->done, async_list) {
> >> 
> >> +		struct v4l2_async_notifier *subdev_notifier =
> >> +			v4l2_async_find_subdev_notifier(sd);
> >> +
> >> +		if (subdev_notifier)
> >> +			v4l2_async_notifier_unbind_all_subdevs(subdev_notifier);
> >> +
> >>  		v4l2_async_cleanup(sd);
> >>  		
> >>  		v4l2_async_notifier_call_unbind(notifier, sd, sd->asd);
> >> -	}
> >> 
> >> -	mutex_unlock(&list_lock);
> >> +		list_del(&sd->async_list);
> >> +		list_add(&sd->async_list, &subdev_list);
> > 
> > How about list_move() ?
> 
> Yeah.
> 
> > This seems to be new code, and by the look of it, I wonder whether it
> > doesn't belong in the reprobing removal patch.
> 
> This is not related to re-probing. Here we're moving an async sub-device
> back to the global sub-device list when its notifier is going away.

In order to make the subdev bindable again when the notifier will be re-
registered. This wasn't needed before, as reprobing took care of that.

> >> +	}
> >> 
> >> +	notifier->parent = NULL;
> >> +	notifier->sd = NULL;
> >>  	notifier->v4l2_dev = NULL;
> >>  }

-- 
Regards,

Laurent Pinchart

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