media: v4l2-ctrls: add core request support

Integrate the request support. This adds the v4l2_ctrl_request_complete
and v4l2_ctrl_request_setup functions to complete a request and (as a
helper function) to apply a request to the hardware.

It takes care of queuing requests and correctly chaining control values
in the request queue.

Note that when a request is marked completed it will copy control values
to the internal request state. This can be optimized in the future since
this is sub-optimal when dealing with large compound and/or array controls.

For the initial 'stateless codec' use-case the current implementation is
sufficient.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/v4l2-core/v4l2-ctrls.c

@@ -1668,6 +1668,13 @@ static int new_to_user(struct v4l2_ext_control *c,
 	return ptr_to_user(c, ctrl, ctrl->p_new);
 }
 
+/* Helper function: copy the request value back to the caller */
+static int req_to_user(struct v4l2_ext_control *c,
+		       struct v4l2_ctrl_ref *ref)
+{
+	return ptr_to_user(c, ref->ctrl, ref->p_req);
+}
+
 /* Helper function: copy the initial control value back to the caller */
 static int def_to_user(struct v4l2_ext_control *c, struct v4l2_ctrl *ctrl)
 {
@@ -1787,6 +1794,26 @@ static void cur_to_new(struct v4l2_ctrl *ctrl)
 	ptr_to_ptr(ctrl, ctrl->p_cur, ctrl->p_new);
 }
 
+/* Copy the new value to the request value */
+static void new_to_req(struct v4l2_ctrl_ref *ref)
+{
+	if (!ref)
+		return;
+	ptr_to_ptr(ref->ctrl, ref->ctrl->p_new, ref->p_req);
+	ref->req = ref;
+}
+
+/* Copy the request value to the new value */
+static void req_to_new(struct v4l2_ctrl_ref *ref)
+{
+	if (!ref)
+		return;
+	if (ref->req)
+		ptr_to_ptr(ref->ctrl, ref->req->p_req, ref->ctrl->p_new);
+	else
+		ptr_to_ptr(ref->ctrl, ref->ctrl->p_cur, ref->ctrl->p_new);
+}
+
 /* Return non-zero if one or more of the controls in the cluster has a new
    value that differs from the current value. */
 static int cluster_changed(struct v4l2_ctrl *master)
@@ -1896,6 +1923,9 @@ int v4l2_ctrl_handler_init_class(struct v4l2_ctrl_handler *hdl,
 	lockdep_set_class_and_name(hdl->lock, key, name);
 	INIT_LIST_HEAD(&hdl->ctrls);
 	INIT_LIST_HEAD(&hdl->ctrl_refs);
+	INIT_LIST_HEAD(&hdl->requests);
+	INIT_LIST_HEAD(&hdl->requests_queued);
+	hdl->request_is_queued = false;
 	hdl->nr_of_buckets = 1 + nr_of_controls_hint / 8;
 	hdl->buckets = kvmalloc_array(hdl->nr_of_buckets,
 				      sizeof(hdl->buckets[0]),
@@ -1916,6 +1946,14 @@ void v4l2_ctrl_handler_free(struct v4l2_ctrl_handler *hdl)
 	if (hdl == NULL || hdl->buckets == NULL)
 		return;
 
+	if (!hdl->req_obj.req && !list_empty(&hdl->requests)) {
+		struct v4l2_ctrl_handler *req, *next_req;
+
+		list_for_each_entry_safe(req, next_req, &hdl->requests, requests) {
+			media_request_object_unbind(&req->req_obj);
+			media_request_object_put(&req->req_obj);
+		}
+	}
 	mutex_lock(hdl->lock);
 	/* Free all nodes */
 	list_for_each_entry_safe(ref, next_ref, &hdl->ctrl_refs, node) {
@@ -2837,6 +2875,123 @@ int v4l2_querymenu(struct v4l2_ctrl_handler *hdl, struct v4l2_querymenu *qm)
 }
 EXPORT_SYMBOL(v4l2_querymenu);
 
+static int v4l2_ctrl_request_clone(struct v4l2_ctrl_handler *hdl,
+				   const struct v4l2_ctrl_handler *from)
+{
+	struct v4l2_ctrl_ref *ref;
+	int err;
+
+	if (WARN_ON(!hdl || hdl == from))
+		return -EINVAL;
+
+	if (hdl->error)
+		return hdl->error;
+
+	WARN_ON(hdl->lock != &hdl->_lock);
+
+	mutex_lock(from->lock);
+	list_for_each_entry(ref, &from->ctrl_refs, node) {
+		struct v4l2_ctrl *ctrl = ref->ctrl;
+		struct v4l2_ctrl_ref *new_ref;
+
+		/* Skip refs inherited from other devices */
+		if (ref->from_other_dev)
+			continue;
+		/* And buttons */
+		if (ctrl->type == V4L2_CTRL_TYPE_BUTTON)
+			continue;
+		err = handler_new_ref(hdl, ctrl, &new_ref, false, true);
+		if (err)
+			break;
+	}
+	mutex_unlock(from->lock);
+	return err;
+}
+
+static void v4l2_ctrl_request_queue(struct media_request_object *obj)
+{
+	struct v4l2_ctrl_handler *hdl =
+		container_of(obj, struct v4l2_ctrl_handler, req_obj);
+	struct v4l2_ctrl_handler *main_hdl = obj->priv;
+	struct v4l2_ctrl_handler *prev_hdl = NULL;
+	struct v4l2_ctrl_ref *ref_ctrl, *ref_ctrl_prev = NULL;
+
+	if (list_empty(&main_hdl->requests_queued))
+		goto queue;
+
+	prev_hdl = list_last_entry(&main_hdl->requests_queued,
+				   struct v4l2_ctrl_handler, requests_queued);
+	/*
+	 * Note: prev_hdl and hdl must contain the same list of control
+	 * references, so if any differences are detected then that is a
+	 * driver bug and the WARN_ON is triggered.
+	 */
+	mutex_lock(prev_hdl->lock);
+	ref_ctrl_prev = list_first_entry(&prev_hdl->ctrl_refs,
+					 struct v4l2_ctrl_ref, node);
+	list_for_each_entry(ref_ctrl, &hdl->ctrl_refs, node) {
+		if (ref_ctrl->req)
+			continue;
+		while (ref_ctrl_prev->ctrl->id < ref_ctrl->ctrl->id) {
+			/* Should never happen, but just in case... */
+			if (list_is_last(&ref_ctrl_prev->node,
+					 &prev_hdl->ctrl_refs))
+				break;
+			ref_ctrl_prev = list_next_entry(ref_ctrl_prev, node);
+		}
+		if (WARN_ON(ref_ctrl_prev->ctrl->id != ref_ctrl->ctrl->id))
+			break;
+		ref_ctrl->req = ref_ctrl_prev->req;
+	}
+	mutex_unlock(prev_hdl->lock);
+queue:
+	list_add_tail(&hdl->requests_queued, &main_hdl->requests_queued);
+	hdl->request_is_queued = true;
+}
+
+static void v4l2_ctrl_request_unbind(struct media_request_object *obj)
+{
+	struct v4l2_ctrl_handler *hdl =
+		container_of(obj, struct v4l2_ctrl_handler, req_obj);
+
+	list_del_init(&hdl->requests);
+	if (hdl->request_is_queued) {
+		list_del_init(&hdl->requests_queued);
+		hdl->request_is_queued = false;
+	}
+}
+
+static void v4l2_ctrl_request_release(struct media_request_object *obj)
+{
+	struct v4l2_ctrl_handler *hdl =
+		container_of(obj, struct v4l2_ctrl_handler, req_obj);
+
+	v4l2_ctrl_handler_free(hdl);
+	kfree(hdl);
+}
+
+static const struct media_request_object_ops req_ops = {
+	.queue = v4l2_ctrl_request_queue,
+	.unbind = v4l2_ctrl_request_unbind,
+	.release = v4l2_ctrl_request_release,
+};
+
+static int v4l2_ctrl_request_bind(struct media_request *req,
+			   struct v4l2_ctrl_handler *hdl,
+			   struct v4l2_ctrl_handler *from)
+{
+	int ret;
+
+	ret = v4l2_ctrl_request_clone(hdl, from);
+
+	if (!ret) {
+		ret = media_request_object_bind(req, &req_ops,
+						from, false, &hdl->req_obj);
+		if (!ret)
+			list_add_tail(&hdl->requests, &from->requests);
+	}
+	return ret;
+}
 
 /* Some general notes on the atomic requirements of VIDIOC_G/TRY/S_EXT_CTRLS:
 
@@ -2898,6 +3053,7 @@ static int prepare_ext_ctrls(struct v4l2_ctrl_handler *hdl,
 
 		if (cs->which &&
 		    cs->which != V4L2_CTRL_WHICH_DEF_VAL &&
+		    cs->which != V4L2_CTRL_WHICH_REQUEST_VAL &&
 		    V4L2_CTRL_ID2WHICH(id) != cs->which)
 			return -EINVAL;
 
@@ -2977,13 +3133,12 @@ static int prepare_ext_ctrls(struct v4l2_ctrl_handler *hdl,
    whether there are any controls at all. */
 static int class_check(struct v4l2_ctrl_handler *hdl, u32 which)
 {
-	if (which == 0 || which == V4L2_CTRL_WHICH_DEF_VAL)
+	if (which == 0 || which == V4L2_CTRL_WHICH_DEF_VAL ||
+	    which == V4L2_CTRL_WHICH_REQUEST_VAL)
 		return 0;
 	return find_ref_lock(hdl, which | 1) ? 0 : -EINVAL;
 }
 
-
-
 /* Get extended controls. Allocates the helpers array if needed. */
 int v4l2_g_ext_ctrls(struct v4l2_ctrl_handler *hdl, struct v4l2_ext_controls *cs)
 {
@@ -3049,8 +3204,12 @@ int v4l2_g_ext_ctrls(struct v4l2_ctrl_handler *hdl, struct v4l2_ext_controls *cs
 			u32 idx = i;
 
 			do {
-				ret = ctrl_to_user(cs->controls + idx,
+				if (helpers[idx].ref->req)
-						   helpers[idx].ref->ctrl);
+					ret = req_to_user(cs->controls + idx,
+						helpers[idx].ref->req);
+				else
+					ret = ctrl_to_user(cs->controls + idx,
+						helpers[idx].ref->ctrl);
 				idx = helpers[idx].next;
 			} while (!ret && idx);
 		}
@@ -3336,7 +3495,16 @@ static int try_set_ext_ctrls(struct v4l2_fh *fh, struct v4l2_ctrl_handler *hdl,
 		} while (!ret && idx);
 
 		if (!ret)
-			ret = try_or_set_cluster(fh, master, set, 0);
+			ret = try_or_set_cluster(fh, master,
+						 !hdl->req_obj.req && set, 0);
+		if (!ret && hdl->req_obj.req && set) {
+			for (j = 0; j < master->ncontrols; j++) {
+				struct v4l2_ctrl_ref *ref =
+					find_ref(hdl, master->cluster[j]->id);
+
+				new_to_req(ref);
+			}
+		}
 
 		/* Copy the new values back to userspace. */
 		if (!ret) {
@@ -3463,6 +3631,162 @@ int __v4l2_ctrl_s_ctrl_string(struct v4l2_ctrl *ctrl, const char *s)
 }
 EXPORT_SYMBOL(__v4l2_ctrl_s_ctrl_string);
 
+void v4l2_ctrl_request_complete(struct media_request *req,
+				struct v4l2_ctrl_handler *main_hdl)
+{
+	struct media_request_object *obj;
+	struct v4l2_ctrl_handler *hdl;
+	struct v4l2_ctrl_ref *ref;
+
+	if (!req || !main_hdl)
+		return;
+
+	/*
+	 * Note that it is valid if nothing was found. It means
+	 * that this request doesn't have any controls and so just
+	 * wants to leave the controls unchanged.
+	 */
+	obj = media_request_object_find(req, &req_ops, main_hdl);
+	if (!obj)
+		return;
+	hdl = container_of(obj, struct v4l2_ctrl_handler, req_obj);
+
+	list_for_each_entry(ref, &hdl->ctrl_refs, node) {
+		struct v4l2_ctrl *ctrl = ref->ctrl;
+		struct v4l2_ctrl *master = ctrl->cluster[0];
+		unsigned int i;
+
+		if (ctrl->flags & V4L2_CTRL_FLAG_VOLATILE) {
+			ref->req = ref;
+
+			v4l2_ctrl_lock(master);
+			/* g_volatile_ctrl will update the current control values */
+			for (i = 0; i < master->ncontrols; i++)
+				cur_to_new(master->cluster[i]);
+			call_op(master, g_volatile_ctrl);
+			new_to_req(ref);
+			v4l2_ctrl_unlock(master);
+			continue;
+		}
+		if (ref->req == ref)
+			continue;
+
+		v4l2_ctrl_lock(ctrl);
+		if (ref->req)
+			ptr_to_ptr(ctrl, ref->req->p_req, ref->p_req);
+		else
+			ptr_to_ptr(ctrl, ctrl->p_cur, ref->p_req);
+		v4l2_ctrl_unlock(ctrl);
+	}
+
+	WARN_ON(!hdl->request_is_queued);
+	list_del_init(&hdl->requests_queued);
+	hdl->request_is_queued = false;
+	media_request_object_complete(obj);
+	media_request_object_put(obj);
+}
+EXPORT_SYMBOL(v4l2_ctrl_request_complete);
+
+void v4l2_ctrl_request_setup(struct media_request *req,
+			     struct v4l2_ctrl_handler *main_hdl)
+{
+	struct media_request_object *obj;
+	struct v4l2_ctrl_handler *hdl;
+	struct v4l2_ctrl_ref *ref;
+
+	if (!req || !main_hdl)
+		return;
+
+	if (WARN_ON(req->state != MEDIA_REQUEST_STATE_QUEUED))
+		return;
+
+	/*
+	 * Note that it is valid if nothing was found. It means
+	 * that this request doesn't have any controls and so just
+	 * wants to leave the controls unchanged.
+	 */
+	obj = media_request_object_find(req, &req_ops, main_hdl);
+	if (!obj)
+		return;
+	if (obj->completed) {
+		media_request_object_put(obj);
+		return;
+	}
+	hdl = container_of(obj, struct v4l2_ctrl_handler, req_obj);
+
+	list_for_each_entry(ref, &hdl->ctrl_refs, node)
+		ref->req_done = false;
+
+	list_for_each_entry(ref, &hdl->ctrl_refs, node) {
+		struct v4l2_ctrl *ctrl = ref->ctrl;
+		struct v4l2_ctrl *master = ctrl->cluster[0];
+		bool have_new_data = false;
+		int i;
+
+		/*
+		 * Skip if this control was already handled by a cluster.
+		 * Skip button controls and read-only controls.
+		 */
+		if (ref->req_done || ctrl->type == V4L2_CTRL_TYPE_BUTTON ||
+		    (ctrl->flags & V4L2_CTRL_FLAG_READ_ONLY))
+			continue;
+
+		v4l2_ctrl_lock(master);
+		for (i = 0; i < master->ncontrols; i++) {
+			if (master->cluster[i]) {
+				struct v4l2_ctrl_ref *r =
+					find_ref(hdl, master->cluster[i]->id);
+
+				if (r->req && r == r->req) {
+					have_new_data = true;
+					break;
+				}
+			}
+		}
+		if (!have_new_data) {
+			v4l2_ctrl_unlock(master);
+			continue;
+		}
+
+		for (i = 0; i < master->ncontrols; i++) {
+			if (master->cluster[i]) {
+				struct v4l2_ctrl_ref *r =
+					find_ref(hdl, master->cluster[i]->id);
+
+				req_to_new(r);
+				master->cluster[i]->is_new = 1;
+				r->req_done = true;
+			}
+		}
+		/*
+		 * For volatile autoclusters that are currently in auto mode
+		 * we need to discover if it will be set to manual mode.
+		 * If so, then we have to copy the current volatile values
+		 * first since those will become the new manual values (which
+		 * may be overwritten by explicit new values from this set
+		 * of controls).
+		 */
+		if (master->is_auto && master->has_volatiles &&
+		    !is_cur_manual(master)) {
+			s32 new_auto_val = *master->p_new.p_s32;
+
+			/*
+			 * If the new value == the manual value, then copy
+			 * the current volatile values.
+			 */
+			if (new_auto_val == master->manual_mode_value)
+				update_from_auto_cluster(master);
+		}
+
+		try_or_set_cluster(NULL, master, true, 0);
+
+		v4l2_ctrl_unlock(master);
+	}
+
+	media_request_object_put(obj);
+}
+EXPORT_SYMBOL(v4l2_ctrl_request_setup);
+
 void v4l2_ctrl_notify(struct v4l2_ctrl *ctrl, v4l2_ctrl_notify_fnc notify, void *priv)
 {
 	if (ctrl == NULL)

include/media/v4l2-ctrls.h

@@ -250,6 +250,12 @@ struct v4l2_ctrl {
  *		``prepare_ext_ctrls`` function at ``v4l2-ctrl.c``.
  * @from_other_dev: If true, then @ctrl was defined in another
  *		device than the &struct v4l2_ctrl_handler.
+ * @req_done:	Internal flag: if the control handler containing this control
+ *		reference is bound to a media request, then this is set when
+ *		the control has been applied. This prevents applying controls
+ *		from a cluster with multiple controls twice (when the first
+ *		control of a cluster is applied, they all are).
+ * @req:	If set, this refers to another request that sets this control.
  * @p_req:	If the control handler containing this control reference
  *		is bound to a media request, then this points to the
  *		value of the control that should be applied when the request
@@ -266,6 +272,8 @@ struct v4l2_ctrl_ref {
 	struct v4l2_ctrl *ctrl;
 	struct v4l2_ctrl_helper *helper;
 	bool from_other_dev;
+	bool req_done;
+	struct v4l2_ctrl_ref *req;
 	union v4l2_ctrl_ptr p_req;
 };
 
@@ -290,6 +298,15 @@ struct v4l2_ctrl_ref {
  * @notify_priv: Passed as argument to the v4l2_ctrl notify callback.
  * @nr_of_buckets: Total number of buckets in the array.
  * @error:	The error code of the first failed control addition.
+ * @request_is_queued: True if the request was queued.
+ * @requests:	List to keep track of open control handler request objects.
+ *		For the parent control handler (@req_obj.req == NULL) this
+ *		is the list header. When the parent control handler is
+ *		removed, it has to unbind and put all these requests since
+ *		they refer to the parent.
+ * @requests_queued: List of the queued requests. This determines the order
+ *		in which these controls are applied. Once the request is
+ *		completed it is removed from this list.
  * @req_obj:	The &struct media_request_object, used to link into a
  *		&struct media_request. This request object has a refcount.
  */
@@ -304,6 +321,9 @@ struct v4l2_ctrl_handler {
 	void *notify_priv;
 	u16 nr_of_buckets;
 	int error;
+	bool request_is_queued;
+	struct list_head requests;
+	struct list_head requests_queued;
 	struct media_request_object req_obj;
 };
 
@@ -1062,6 +1082,37 @@ int v4l2_ctrl_subscribe_event(struct v4l2_fh *fh,
  */
 __poll_t v4l2_ctrl_poll(struct file *file, struct poll_table_struct *wait);
 
+/**
+ * v4l2_ctrl_request_setup - helper function to apply control values in a request
+ *
+ * @req: The request
+ * @parent: The parent control handler ('priv' in media_request_object_find())
+ *
+ * This is a helper function to call the control handler's s_ctrl callback with
+ * the control values contained in the request. Do note that this approach of
+ * applying control values in a request is only applicable to memory-to-memory
+ * devices.
+ */
+void v4l2_ctrl_request_setup(struct media_request *req,
+			     struct v4l2_ctrl_handler *parent);
+
+/**
+ * v4l2_ctrl_request_complete - Complete a control handler request object
+ *
+ * @req: The request
+ * @parent: The parent control handler ('priv' in media_request_object_find())
+ *
+ * This function is to be called on each control handler that may have had a
+ * request object associated with it, i.e. control handlers of a driver that
+ * supports requests.
+ *
+ * The function first obtains the values of any volatile controls in the control
+ * handler and attach them to the request. Then, the function completes the
+ * request object.
+ */
+void v4l2_ctrl_request_complete(struct media_request *req,
+				struct v4l2_ctrl_handler *hdl);
+
 /* Helpers for ioctl_ops */
 
 /**