diff mbox

[v16,16/32] v4l: async: Allow async notifier register call succeed with no subdevs

Message ID 20171026075342.5760-17-sakari.ailus@linux.intel.com (mailing list archive)
State New, archived
Headers show

Commit Message

Sakari Ailus Oct. 26, 2017, 7:53 a.m. UTC 
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@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 drivers/media/v4l2-core/v4l2-async.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

Comments

Niklas Söderlund Oct. 26, 2017, 10 p.m. UTC | #1 
On 2017-10-26 10:53:26 +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@linux.intel.com>
> Acked-by: Hans Verkuil <hans.verkuil@cisco.com>

Acked-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

> ---
>  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(&notifier->waiting);
>  	INIT_LIST_HEAD(&notifier->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
>
Sebastian Reichel Oct. 27, 2017, 2:49 p.m. UTC | #2 
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@linux.intel.com>
> Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
> ---

Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>

-- Sebastian

>  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(&notifier->waiting);
>  	INIT_LIST_HEAD(&notifier->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
>
diff mbox

Patch

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(&notifier->waiting);
 	INIT_LIST_HEAD(&notifier->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];