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@xxxxxxxxxxxxxxxx>
> ---
> 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
