diff mbox series

[v6,20/24] v4l: subdev: routing kernel helper functions

Message ID 20210427124523.990938-21-tomi.valkeinen@ideasonboard.com
State Superseded
Headers show
Series v4l: subdev internal routing | expand

Commit Message

Tomi Valkeinen April 27, 2021, 12:45 p.m. UTC 
Add helper functions for routing.

TODO: add docs.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 drivers/media/v4l2-core/v4l2-subdev.c | 90 +++++++++++++++++++++++++++
 include/media/v4l2-subdev.h           | 14 +++++
 2 files changed, 104 insertions(+)

Comments

Laurent Pinchart April 29, 2021, 3:46 a.m. UTC | #1 
Hi Tomi,

Thank you for the patch.

On Tue, Apr 27, 2021 at 03:45:19PM +0300, Tomi Valkeinen wrote:
> Add helper functions for routing.

> 

> TODO: add docs.

> 

> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>

> ---

>  drivers/media/v4l2-core/v4l2-subdev.c | 90 +++++++++++++++++++++++++++

>  include/media/v4l2-subdev.h           | 14 +++++

>  2 files changed, 104 insertions(+)

> 

> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c

> index ad79ce121cee..31e279292ea6 100644

> --- a/drivers/media/v4l2-core/v4l2-subdev.c

> +++ b/drivers/media/v4l2-core/v4l2-subdev.c

> @@ -910,6 +910,96 @@ v4l2_subdev_link_validate_get_format(struct media_pad *pad,

>  	return -EINVAL;

>  }

>  

> +int v4l2_subdev_get_krouting(struct v4l2_subdev *sd,


I wonder if we could call the function v4l2_subdev_get_routing(), the
functions below don't have a k prefix.

> +			     struct v4l2_subdev_krouting *routing)

> +{

> +	int ret;

> +

> +	routing->which = V4L2_SUBDEV_FORMAT_ACTIVE;

> +	routing->routes = NULL;

> +	routing->num_routes = 0;

> +

> +	ret = v4l2_subdev_call(sd, pad, get_routing, routing);

> +	if (ret == 0)

> +		return 0;

> +	if (ret != -ENOSPC)

> +		return ret;

> +

> +	routing->routes = kvmalloc_array(routing->num_routes,

> +					 sizeof(*routing->routes), GFP_KERNEL);

> +	if (!routing->routes)

> +		return -ENOMEM;

> +

> +	ret = v4l2_subdev_call(sd, pad, get_routing, routing);

> +	if (ret) {

> +		kvfree(routing->routes);


Should we handle the case where the subdev configuration gets changed
between the two calls, and the number of routes increases ? If that can
happen, there's also a risk for the routing configuration to be stale
already when this function returns, so it's probably the caller that
needs to ensure this can't happen.

> +		return ret;

> +	}

> +

> +	return 0;

> +}

> +EXPORT_SYMBOL_GPL(v4l2_subdev_get_krouting);

> +

> +void v4l2_subdev_free_routing(struct v4l2_subdev_krouting *routing)

> +{

> +	kvfree(routing->routes);

> +	routing->routes = NULL;


I'd set num_routes to 0 too.

> +}

> +EXPORT_SYMBOL_GPL(v4l2_subdev_free_routing);

> +

> +void v4l2_subdev_cpy_routing(struct v4l2_subdev_krouting *dst,

> +			     const struct v4l2_subdev_krouting *src)

> +{

> +	memcpy(dst->routes, src->routes,

> +	       src->num_routes * sizeof(*src->routes));


Is there a guarantee that dst has allocated enough entries in routes ?
It seems a bit fragile.

> +	dst->num_routes = src->num_routes;

> +	dst->which = src->which;

> +}

> +EXPORT_SYMBOL_GPL(v4l2_subdev_cpy_routing);

> +

> +int v4l2_subdev_dup_routing(struct v4l2_subdev_krouting *dst,

> +			    const struct v4l2_subdev_krouting *src)

> +{

> +	if (dst->routes)

> +		kvfree(dst->routes);


I'd set routes to NULL and num_routes to 0 here, so that num_routes
would be 0 if the allocation fails below. The performance impact will be
negligible, and the data will be more coherent. We could set num_routes
to 0 in the allocation error path, but splitting the kvfree() and the
routes and num_routes assignments opens the door to more bugs when this
function will be extended/refactored.

> +

> +	if (src->num_routes == 0) {

> +		dst->which = src->which;

> +		dst->routes = NULL;

> +		dst->num_routes = 0;

> +		return 0;

> +	}

> +

> +	dst->routes = kvmalloc_array(src->num_routes, sizeof(*src->routes),

> +				     GFP_KERNEL);

> +	if (!dst->routes)

> +		return -ENOMEM;

> +

> +	v4l2_subdev_cpy_routing(dst, src);

> +

> +	return 0;

> +}

> +EXPORT_SYMBOL_GPL(v4l2_subdev_dup_routing);

> +

> +bool v4l2_subdev_has_route(struct v4l2_subdev_krouting *routing,

> +			   unsigned int pad0, unsigned int pad1)

> +{

> +	unsigned int i;

> +

> +	for (i = 0; i < routing->num_routes; ++i) {

> +		struct v4l2_subdev_route *route = &routing->routes[i];

> +

> +		if (!(route->flags & V4L2_SUBDEV_ROUTE_FL_ACTIVE))

> +			continue;

> +

> +		if (route->sink_pad == pad0 && route->source_pad == pad1)


pad0 and pad1 should be renamed to sink_pad and source_pad if that's how
they need to be used. Given that this function is called in the media
entity .has_route() operation, which only guarantees that pad0 < pad 1,
we probably want to support the case where pad0 is a source pad and pad1
a sink pad.

I'm trying to recall why the media entity operation was designed this
way, and I think it was meant to support testing if two sink pads or two
source pads are connected by routes, indirectly. For instance, if a
subdev has one sink pad A and two source pads B and C, active routes
from A to B and from A to C should result in .has_route(B, C) returning
true. If I remember correctly, this was needed by the graph traversal
code, but that would need to be double-checked.

> +			return true;

> +	}

> +

> +	return false;

> +}

> +EXPORT_SYMBOL_GPL(v4l2_subdev_has_route);

> +

>  int v4l2_subdev_link_validate(struct media_link *link)

>  {

>  	struct v4l2_subdev *sink;

> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h

> index c45f5f0156c9..1235d4832b76 100644

> --- a/include/media/v4l2-subdev.h

> +++ b/include/media/v4l2-subdev.h

> @@ -1235,4 +1235,18 @@ extern const struct v4l2_subdev_ops v4l2_subdev_call_wrappers;

>  void v4l2_subdev_notify_event(struct v4l2_subdev *sd,

>  			      const struct v4l2_event *ev);

>  

> +int v4l2_subdev_get_krouting(struct v4l2_subdev *sd,

> +			     struct v4l2_subdev_krouting *routing);

> +

> +void v4l2_subdev_free_routing(struct v4l2_subdev_krouting *routing);

> +

> +int v4l2_subdev_dup_routing(struct v4l2_subdev_krouting *dst,

> +			    const struct v4l2_subdev_krouting *src);

> +

> +void v4l2_subdev_cpy_routing(struct v4l2_subdev_krouting *dst,

> +			     const struct v4l2_subdev_krouting *src);

> +

> +bool v4l2_subdev_has_route(struct v4l2_subdev_krouting *routing,

> +			   unsigned int pad0, unsigned int pad1);

> +

>  #endif


-- 
Regards,

Laurent Pinchart
diff mbox series

Patch

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index ad79ce121cee..31e279292ea6 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -910,6 +910,96 @@  v4l2_subdev_link_validate_get_format(struct media_pad *pad,
 	return -EINVAL;
 }
 
+int v4l2_subdev_get_krouting(struct v4l2_subdev *sd,
+			     struct v4l2_subdev_krouting *routing)
+{
+	int ret;
+
+	routing->which = V4L2_SUBDEV_FORMAT_ACTIVE;
+	routing->routes = NULL;
+	routing->num_routes = 0;
+
+	ret = v4l2_subdev_call(sd, pad, get_routing, routing);
+	if (ret == 0)
+		return 0;
+	if (ret != -ENOSPC)
+		return ret;
+
+	routing->routes = kvmalloc_array(routing->num_routes,
+					 sizeof(*routing->routes), GFP_KERNEL);
+	if (!routing->routes)
+		return -ENOMEM;
+
+	ret = v4l2_subdev_call(sd, pad, get_routing, routing);
+	if (ret) {
+		kvfree(routing->routes);
+		return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_get_krouting);
+
+void v4l2_subdev_free_routing(struct v4l2_subdev_krouting *routing)
+{
+	kvfree(routing->routes);
+	routing->routes = NULL;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_free_routing);
+
+void v4l2_subdev_cpy_routing(struct v4l2_subdev_krouting *dst,
+			     const struct v4l2_subdev_krouting *src)
+{
+	memcpy(dst->routes, src->routes,
+	       src->num_routes * sizeof(*src->routes));
+	dst->num_routes = src->num_routes;
+	dst->which = src->which;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_cpy_routing);
+
+int v4l2_subdev_dup_routing(struct v4l2_subdev_krouting *dst,
+			    const struct v4l2_subdev_krouting *src)
+{
+	if (dst->routes)
+		kvfree(dst->routes);
+
+	if (src->num_routes == 0) {
+		dst->which = src->which;
+		dst->routes = NULL;
+		dst->num_routes = 0;
+		return 0;
+	}
+
+	dst->routes = kvmalloc_array(src->num_routes, sizeof(*src->routes),
+				     GFP_KERNEL);
+	if (!dst->routes)
+		return -ENOMEM;
+
+	v4l2_subdev_cpy_routing(dst, src);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_dup_routing);
+
+bool v4l2_subdev_has_route(struct v4l2_subdev_krouting *routing,
+			   unsigned int pad0, unsigned int pad1)
+{
+	unsigned int i;
+
+	for (i = 0; i < routing->num_routes; ++i) {
+		struct v4l2_subdev_route *route = &routing->routes[i];
+
+		if (!(route->flags & V4L2_SUBDEV_ROUTE_FL_ACTIVE))
+			continue;
+
+		if (route->sink_pad == pad0 && route->source_pad == pad1)
+			return true;
+	}
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_has_route);
+
 int v4l2_subdev_link_validate(struct media_link *link)
 {
 	struct v4l2_subdev *sink;
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index c45f5f0156c9..1235d4832b76 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -1235,4 +1235,18 @@  extern const struct v4l2_subdev_ops v4l2_subdev_call_wrappers;
 void v4l2_subdev_notify_event(struct v4l2_subdev *sd,
 			      const struct v4l2_event *ev);
 
+int v4l2_subdev_get_krouting(struct v4l2_subdev *sd,
+			     struct v4l2_subdev_krouting *routing);
+
+void v4l2_subdev_free_routing(struct v4l2_subdev_krouting *routing);
+
+int v4l2_subdev_dup_routing(struct v4l2_subdev_krouting *dst,
+			    const struct v4l2_subdev_krouting *src);
+
+void v4l2_subdev_cpy_routing(struct v4l2_subdev_krouting *dst,
+			     const struct v4l2_subdev_krouting *src);
+
+bool v4l2_subdev_has_route(struct v4l2_subdev_krouting *routing,
+			   unsigned int pad0, unsigned int pad1);
+
 #endif