diff options
| -rw-r--r-- | Documentation/video4linux/v4l2-controls.txt | 22 | ||||
| -rw-r--r-- | drivers/media/v4l2-core/v4l2-ctrls.c | 18 | ||||
| -rw-r--r-- | include/media/v4l2-ctrls.h | 25 |
3 files changed, 57 insertions, 8 deletions
diff --git a/Documentation/video4linux/v4l2-controls.txt b/Documentation/video4linux/v4l2-controls.txt index cfe52c798d74..676f87366025 100644 --- a/Documentation/video4linux/v4l2-controls.txt +++ b/Documentation/video4linux/v4l2-controls.txt @@ -715,14 +715,20 @@ a control of this type whenever the first control belonging to a new control class is added. -Proposals for Extensions -======================== +Adding Notify Callbacks +======================= + +Sometimes the platform or bridge driver needs to be notified when a control +from a sub-device driver changes. You can set a notify callback by calling +this function: -Some ideas for future extensions to the spec: +void v4l2_ctrl_notify(struct v4l2_ctrl *ctrl, + void (*notify)(struct v4l2_ctrl *ctrl, void *priv), void *priv); -1) Add a V4L2_CTRL_FLAG_HEX to have values shown as hexadecimal instead of -decimal. Useful for e.g. video_mute_yuv. +Whenever the give control changes value the notify callback will be called +with a pointer to the control and the priv pointer that was passed with +v4l2_ctrl_notify. Note that the control's handler lock is held when the +notify function is called. -2) It is possible to mark in the controls array which controls have been -successfully written and which failed by for example adding a bit to the -control ID. Not sure if it is worth the effort, though. +There can be only one notify function per control handler. Any attempt +to set another notify function will cause a WARN_ON. diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c index f6ee201d9347..fa02363e7db4 100644 --- a/drivers/media/v4l2-core/v4l2-ctrls.c +++ b/drivers/media/v4l2-core/v4l2-ctrls.c @@ -1204,6 +1204,8 @@ static void new_to_cur(struct v4l2_fh *fh, struct v4l2_ctrl *ctrl, send_event(fh, ctrl, (changed ? V4L2_EVENT_CTRL_CH_VALUE : 0) | (update_inactive ? V4L2_EVENT_CTRL_CH_FLAGS : 0)); + if (ctrl->call_notify && changed && ctrl->handler->notify) + ctrl->handler->notify(ctrl, ctrl->handler->notify_priv); } } @@ -2725,6 +2727,22 @@ int v4l2_ctrl_s_ctrl_int64(struct v4l2_ctrl *ctrl, s64 val) } EXPORT_SYMBOL(v4l2_ctrl_s_ctrl_int64); +void v4l2_ctrl_notify(struct v4l2_ctrl *ctrl, v4l2_ctrl_notify_fnc notify, void *priv) +{ + if (ctrl == NULL) + return; + if (notify == NULL) { + ctrl->call_notify = 0; + return; + } + if (WARN_ON(ctrl->handler->notify && ctrl->handler->notify != notify)) + return; + ctrl->handler->notify = notify; + ctrl->handler->notify_priv = priv; + ctrl->call_notify = 1; +} +EXPORT_SYMBOL(v4l2_ctrl_notify); + static int v4l2_ctrl_add_event(struct v4l2_subscribed_event *sev, unsigned elems) { struct v4l2_ctrl *ctrl = v4l2_ctrl_find(sev->fh->ctrl_handler, sev->id); diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h index 96509119f28f..c4cc04136074 100644 --- a/include/media/v4l2-ctrls.h +++ b/include/media/v4l2-ctrls.h @@ -53,6 +53,8 @@ struct v4l2_ctrl_ops { int (*s_ctrl)(struct v4l2_ctrl *ctrl); }; +typedef void (*v4l2_ctrl_notify_fnc)(struct v4l2_ctrl *ctrl, void *priv); + /** struct v4l2_ctrl - The control structure. * @node: The list node. * @ev_subs: The list of control event subscriptions. @@ -72,6 +74,8 @@ struct v4l2_ctrl_ops { * set this flag directly. * @has_volatiles: If set, then one or more members of the cluster are volatile. * Drivers should never touch this flag. + * @call_notify: If set, then call the handler's notify function whenever the + * control's value changes. * @manual_mode_value: If the is_auto flag is set, then this is the value * of the auto control that determines if that control is in * manual mode. So if the value of the auto control equals this @@ -119,6 +123,7 @@ struct v4l2_ctrl { unsigned int is_private:1; unsigned int is_auto:1; unsigned int has_volatiles:1; + unsigned int call_notify:1; unsigned int manual_mode_value:8; const struct v4l2_ctrl_ops *ops; @@ -177,6 +182,10 @@ 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. + * @notify: A notify callback that is called whenever the control changes value. + * Note that the handler's lock is held when the notify function + * is called! + * @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. */ @@ -187,6 +196,8 @@ struct v4l2_ctrl_handler { struct list_head ctrl_refs; struct v4l2_ctrl_ref *cached; struct v4l2_ctrl_ref **buckets; + v4l2_ctrl_notify_fnc notify; + void *notify_priv; u16 nr_of_buckets; int error; }; @@ -525,6 +536,20 @@ static inline void v4l2_ctrl_unlock(struct v4l2_ctrl *ctrl) mutex_unlock(ctrl->handler->lock); } +/** v4l2_ctrl_notify() - Function to set a notify callback for a control. + * @ctrl: The control. + * @notify: The callback function. + * @priv: The callback private handle, passed as argument to the callback. + * + * This function sets a callback function for the control. If @ctrl is NULL, + * then it will do nothing. If @notify is NULL, then the notify callback will + * be removed. + * + * There can be only one notify. If another already exists, then a WARN_ON + * will be issued and the function will do nothing. + */ +void v4l2_ctrl_notify(struct v4l2_ctrl *ctrl, v4l2_ctrl_notify_fnc notify, void *priv); + /** v4l2_ctrl_g_ctrl() - Helper function to get the control's value from within a driver. * @ctrl: The control. * |
