[PATCH] v4l2-ctrls: add v4l2_ctrl_request_hdl_find/put/ctrl_find functions

[PATCH] v4l2-ctrls: add v4l2_ctrl_request_hdl_find/put/ctrl_find functions

[Hans Verkuil]

If a driver needs to find/inspect the controls set in a request then
it can use these functions.

E.g. to check if a required control is set in a request use this in the
req_validate() implementation:

	int res = -EINVAL;

	hdl = v4l2_ctrl_request_hdl_find(req, parent_hdl);
	if (hdl) {
		if (v4l2_ctrl_request_hdl_ctrl_find(hdl, ctrl_id))
			res = 0;
		v4l2_ctrl_request_hdl_put(hdl);
	}
	return res;

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
---
Paul, please test this. This should be what you need.

Regards,

	Hans
---
diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
index 3ff17c87b3c8..03fd140736fd 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls.c
@@ -2976,6 +2976,31 @@ static const struct media_request_object_ops req_ops = {
 	.release = v4l2_ctrl_request_release,
 };

+struct v4l2_ctrl_handler *v4l2_ctrl_request_hdl_find(struct media_request *req,
+					struct v4l2_ctrl_handler *parent)
+{
+	struct media_request_object *obj;
+	
+	if (WARN_ON(req->state != MEDIA_REQUEST_STATE_VALIDATING &&
+		    req->state != MEDIA_REQUEST_STATE_QUEUED))
+		return NULL;
+
+	obj = media_request_object_find(req, &req_ops, parent);
+	if (obj)
+		return container_of(obj, struct v4l2_ctrl_handler, req_obj);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(v4l2_ctrl_request_hdl_find);
+
+struct v4l2_ctrl *
+v4l2_ctrl_request_hdl_ctrl_find(struct v4l2_ctrl_handler *hdl, u32 id)
+{
+	struct v4l2_ctrl_ref *ref = find_ref_lock(hdl, id);
+
+	return (ref && ref->req == ref) ? ref : NULL;
+}
+EXPORT_SYMBOL_GPL(v4l2_ctrl_request_hdl_ctrl_find);
+
 static int v4l2_ctrl_request_bind(struct media_request *req,
 			   struct v4l2_ctrl_handler *hdl,
 			   struct v4l2_ctrl_handler *from)
diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
index de70cc3a1b80..34ee3167d7dd 100644
--- a/include/media/v4l2-ctrls.h
+++ b/include/media/v4l2-ctrls.h
@@ -1111,7 +1111,49 @@ void v4l2_ctrl_request_setup(struct media_request *req,
  * request object.
  */
 void v4l2_ctrl_request_complete(struct media_request *req,
-				struct v4l2_ctrl_handler *hdl);
+				struct v4l2_ctrl_handler *parent);
+
+/**
+ * v4l2_ctrl_request_hdl_find - Find the control handler in the request
+ *
+ * @req: The request
+ * @parent: The parent control handler ('priv' in media_request_object_find())
+ *
+ * This function finds the control handler in the request. It may return
+ * NULL if not found. When done, you must call v4l2_ctrl_request_put_hdl()
+ * with the returned handler pointer.
+ *
+ * If the request is not in state VALIDATING or QUEUED, then this function
+ * will always return NULL.
+ */
+struct v4l2_ctrl_handler *v4l2_ctrl_request_hdl_find(struct media_request *req,
+					struct v4l2_ctrl_handler *parent);
+
+/**
+ * v4l2_ctrl_request_hdl_put - Put the control handler
+ *
+ * @hdl: Put this control handler
+ *
+ * This function released the control handler previously obtained from'
+ * v4l2_ctrl_request_hdl_find().
+ */
+static inline void v4l2_ctrl_request_hdl_put(struct v4l2_ctrl_handler *hdl)
+{
+	if (hdl)
+		media_request_object_put(&hdl->req_obj);
+}
+
+/**
+ * v4l2_ctrl_request_ctrl_find() - Find a control with the given ID.
+ *
+ * @hdl: The control handler from the request.
+ * @id: The ID of the control to find.
+ *
+ * This function returns a pointer to the control if this control is
+ * part of the request or NULL otherwise.
+ */
+struct v4l2_ctrl *
+v4l2_ctrl_request_hdl_ctrl_find(struct v4l2_ctrl_handler *hdl, u32 id);

 /* Helpers for ioctl_ops */

Re: [PATCH] v4l2-ctrls: add v4l2_ctrl_request_hdl_find/put/ctrl_find functions

[Paul Kocialkowski]

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Hi,

On Wed, 2018-07-04 at 17:38 +0200, Hans Verkuil wrote:
> If a driver needs to find/inspect the controls set in a request then
> it can use these functions.
> 
> E.g. to check if a required control is set in a request use this in the
> req_validate() implementation:
> 
> 	int res = -EINVAL;
> 
> 	hdl = v4l2_ctrl_request_hdl_find(req, parent_hdl);
> 	if (hdl) {
> 		if (v4l2_ctrl_request_hdl_ctrl_find(hdl, ctrl_id))
> 			res = 0;
> 		v4l2_ctrl_request_hdl_put(hdl);
> 	}
> 	return res;

Thanks again for pulling this off, that's definitely what I neeeded!

I was able to test the patch and get it to work with sunxi-cedrus, with
one modification highlighted below.

Note that for my use case, I need to have access to the driver's private
data (context) to get the parent hdl. I'm iterating over request objects
and getting the context from a buffer object (checked via
vb2_request_object_is_buffer), a bit like it's done in
vb2_m2m_request_queue.

> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
> ---
> Paul, please test this. This should be what you need.
> 
> Regards,
> 
> 	Hans
> ---
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
> index 3ff17c87b3c8..03fd140736fd 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
> @@ -2976,6 +2976,31 @@ static const struct media_request_object_ops req_ops = {
>  	.release = v4l2_ctrl_request_release,
>  };
> 
> +struct v4l2_ctrl_handler *v4l2_ctrl_request_hdl_find(struct media_request *req,
> +					struct v4l2_ctrl_handler *parent)
> +{
> +	struct media_request_object *obj;
> +	
> +	if (WARN_ON(req->state != MEDIA_REQUEST_STATE_VALIDATING &&
> +		    req->state != MEDIA_REQUEST_STATE_QUEUED))
> +		return NULL;
> +
> +	obj = media_request_object_find(req, &req_ops, parent);
> +	if (obj)
> +		return container_of(obj, struct v4l2_ctrl_handler, req_obj);
> +	return NULL;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_ctrl_request_hdl_find);
> +
> +struct v4l2_ctrl *
> +v4l2_ctrl_request_hdl_ctrl_find(struct v4l2_ctrl_handler *hdl, u32 id)
> +{
> +	struct v4l2_ctrl_ref *ref = find_ref_lock(hdl, id);
> +
> +	return (ref && ref->req == ref) ? ref : NULL;

When req && ref->req == ref, ref->ctrl should be returned instead of
ref.

Cheers,

Paul
-- 
Paul Kocialkowski, Bootlin (formerly Free Electrons)
Embedded Linux and kernel engineering
https://bootlin.com

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