Re: [PATCH v16 16/32] v4l: async: Allow async notifier register call succeed with no subdevs
From: Sebastian Reichel <hidden>
Date: 2017-10-27 14:49:35
Also in:
linux-acpi, linux-media
Hi, On Thu, Oct 26, 2017 at 10:53:26AM +0300, Sakari Ailus wrote:
The information on how many async sub-devices would be bindable to a notifier is typically dependent on information from platform firmware and it's not driver's business to be aware of that. Many V4L2 main drivers are perfectly usable (and useful) without async sub-devices and so if there aren't any around, just proceed call the notifier's complete callback immediately without registering the notifier itself. If a driver needs to check whether there are async sub-devices available, it can be done by inspecting the notifier's num_subdevs field which tells the number of async sub-devices. Signed-off-by: Sakari Ailus <sakari.ailus-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> Acked-by: Hans Verkuil <redacted> ---
Reviewed-by: Sebastian Reichel <sebastian.reichel-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org> -- Sebastian
quoted hunk
drivers/media/v4l2-core/v4l2-async.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-)diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c index 46db85685894..1b536d68cedf 100644 --- a/drivers/media/v4l2-core/v4l2-async.c +++ b/drivers/media/v4l2-core/v4l2-async.c@@ -180,14 +180,22 @@ int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev, int ret; int i; - if (!v4l2_dev || !notifier->num_subdevs || - notifier->num_subdevs > V4L2_MAX_SUBDEVS) + if (!v4l2_dev || notifier->num_subdevs > V4L2_MAX_SUBDEVS) return -EINVAL; notifier->v4l2_dev = v4l2_dev; INIT_LIST_HEAD(¬ifier->waiting); INIT_LIST_HEAD(¬ifier->done); + if (!notifier->num_subdevs) { + int ret; + + ret = v4l2_async_notifier_call_complete(notifier); + notifier->v4l2_dev = NULL; + + return ret; + } + for (i = 0; i < notifier->num_subdevs; i++) { asd = notifier->subdevs[i];-- 2.11.0
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