From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
---
drivers/media/video/v4l2-ctrls.c | 27 +++++++++++++++++++++++++++
include/media/v4l2-ctrls.h | 28 ++++++++++++++++++++++++++++
2 files changed, 55 insertions(+), 0 deletions(-)
diff --git a/drivers/media/video/v4l2-ctrls.c b/drivers/media/video/v4l2-ctrls.c
index 99987fe..bf649cf 100644
--- a/drivers/media/video/v4l2-ctrls.c
+++ b/drivers/media/video/v4l2-ctrls.c
@@ -862,6 +862,13 @@ int v4l2_ctrl_handler_init(struct v4l2_ctrl_handler *hdl,
}
EXPORT_SYMBOL(v4l2_ctrl_handler_init);
+/* Count the number of controls */
+unsigned v4l2_ctrl_handler_cnt(const struct v4l2_ctrl_handler *hdl)
+{
+ return hdl ? hdl->nr_of_refs : 0;
+}
+EXPORT_SYMBOL(v4l2_ctrl_handler_cnt);
+
/* Free all controls and control refs */
void v4l2_ctrl_handler_free(struct v4l2_ctrl_handler *hdl)
{
@@ -1013,6 +1020,7 @@ static int handler_new_ref(struct v4l2_ctrl_handler *hdl,
insertion is an O(1) operation. */
if (list_empty(&hdl->ctrl_refs) || id > node2id(hdl->ctrl_refs.prev)) {
list_add_tail(&new_ref->node, &hdl->ctrl_refs);
+ hdl->nr_of_refs++;
goto insert_in_hash;
}
@@ -2061,3 +2069,22 @@ void v4l2_ctrl_del_fh(struct v4l2_ctrl *ctrl, struct v4l2_fh *fh)
v4l2_ctrl_unlock(ctrl);
}
EXPORT_SYMBOL(v4l2_ctrl_del_fh);
+
+int v4l2_ctrl_subscribe_fh(struct v4l2_fh *fh,
+ struct v4l2_event_subscription *sub, unsigned n)
+{
+ struct v4l2_ctrl_handler *hdl = fh->ctrl_handler;
+ int ret = 0;
+
+ if (!fh->events)
+ ret = v4l2_event_init(fh);
+ if (!ret) {
+ if (v4l2_ctrl_handler_cnt(hdl) * 2 > n)
+ n = v4l2_ctrl_handler_cnt(hdl) * 2;
+ ret = v4l2_event_alloc(fh, n);
+ }
+ if (!ret)
+ ret = v4l2_event_subscribe(fh, sub);
+ return ret;
+}
+EXPORT_SYMBOL(v4l2_ctrl_subscribe_fh);
diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
index c45bf40..72dafcf 100644
--- a/include/media/v4l2-ctrls.h
+++ b/include/media/v4l2-ctrls.h
@@ -169,6 +169,7 @@ struct v4l2_ctrl_ref {
* control is needed multiple times, so this is a simple
* optimization.
* @buckets: Buckets for the hashing. Allows for quick control lookup.
+ * @nr_of_refs: Total number of control references in the list.
* @nr_of_buckets: Total number of buckets in the array.
* @error: The error code of the first failed control addition.
*/
@@ -178,6 +179,7 @@ struct v4l2_ctrl_handler {
struct list_head ctrl_refs;
struct v4l2_ctrl_ref *cached;
struct v4l2_ctrl_ref **buckets;
+ u16 nr_of_refs;
u16 nr_of_buckets;
int error;
};
@@ -263,6 +265,14 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
int v4l2_ctrl_handler_init(struct v4l2_ctrl_handler *hdl,
unsigned nr_of_controls_hint);
+/** v4l2_ctrl_handler_cnt() - Count the number of controls in the handler.
+ * @hdl: The control handler.
+ *
+ * Returns the number of controls referenced by this handler.
+ * Returns 0 if @hdl == NULL.
+ */
+unsigned v4l2_ctrl_handler_cnt(const struct v4l2_ctrl_handler *hdl);
+
/** v4l2_ctrl_handler_free() - Free all controls owned by the handler and free
* the control list.
* @hdl: The control handler.
@@ -494,11 +504,29 @@ s32 v4l2_ctrl_g_ctrl(struct v4l2_ctrl *ctrl);
*/
int v4l2_ctrl_s_ctrl(struct v4l2_ctrl *ctrl, s32 val);
+/* Internal helper functions that deal with control events. */
void v4l2_ctrl_add_fh(struct v4l2_ctrl_handler *hdl,
struct v4l2_ctrl_fh *ctrl_fh,
struct v4l2_event_subscription *sub);
void v4l2_ctrl_del_fh(struct v4l2_ctrl *ctrl, struct v4l2_fh *fh);
+/** v4l2_ctrl_subscribe_fh() - Helper function that subscribes a control event.
+ * @fh: The file handler that subscribed the control event.
+ * @sub: The event to subscribe (type must be V4L2_EVENT_CTRL).
+ * @n: How many events should be allocated? (Passed to v4l2_event_alloc).
+ * Recommended to set to twice the number of controls plus whatever
+ * is needed for other events. This function will set n to
+ * max(n, 2 * v4l2_ctrl_handler_cnt(fh->ctrl_handler)).
+ *
+ * A helper function that initializes the fh for events, allocates the
+ * list of events and subscribes the control event.
+ *
+ * Typically called in the handler of VIDIOC_SUBSCRIBE_EVENT in the
+ * V4L2_EVENT_CTRL case.
+ */
+int v4l2_ctrl_subscribe_fh(struct v4l2_fh *fh,
+ struct v4l2_event_subscription *sub, unsigned n);
+
/* Helpers for ioctl_ops. If hdl == NULL then they will all return -EINVAL. */
int v4l2_queryctrl(struct v4l2_ctrl_handler *hdl, struct v4l2_queryctrl *qc);
int v4l2_querymenu(struct v4l2_ctrl_handler *hdl, struct v4l2_querymenu *qm);
--
1.7.1
--
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