[media] media/v4l2-core: struct struct v4l2_ext_controls param which

Support for new field which on v4l2_ext_controls, used to get the
default value of one or more controls.

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
index f3fba8661166ebceff32ff8a4441b7e16abeb4c1..c9d5537b6af7a4cc32de8270617237450c47d207 100644 (file)
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls.c
@@ -1491,6 +1491,17 @@ static int new_to_user(struct v4l2_ext_control *c,
        return ptr_to_user(c, ctrl, ctrl->p_new);
 }
 
+/* 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)
+{
+       int idx;
+
+       for (idx = 0; idx < ctrl->elems; idx++)
+               ctrl->type_ops->init(ctrl, idx, ctrl->p_new);
+
+       return ptr_to_user(c, ctrl, ctrl->p_new);
+}
+
 /* Helper function: copy the caller-provider value to the given control value */
 static int user_to_ptr(struct v4l2_ext_control *c,
                       struct v4l2_ctrl *ctrl,
@@ -2710,7 +2721,9 @@ static int prepare_ext_ctrls(struct v4l2_ctrl_handler *hdl,
 
                cs->error_idx = i;
 
-               if (cs->which && V4L2_CTRL_ID2WHICH(id) != cs->which)
+               if (cs->which &&
+                   cs->which != V4L2_CTRL_WHICH_DEF_VAL &&
+                   V4L2_CTRL_ID2WHICH(id) != cs->which)
                        return -EINVAL;
 
                /* Old-style private controls are not allowed for
@@ -2789,7 +2802,7 @@ 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)
+       if (which == 0 || which == V4L2_CTRL_WHICH_DEF_VAL)
                return list_empty(&hdl->ctrl_refs) ? -EINVAL : 0;
        return find_ref_lock(hdl, which | 1) ? 0 : -EINVAL;
 }
@@ -2803,6 +2816,9 @@ int v4l2_g_ext_ctrls(struct v4l2_ctrl_handler *hdl, struct v4l2_ext_controls *cs
        struct v4l2_ctrl_helper *helpers = helper;
        int ret;
        int i, j;
+       bool def_value;
+
+       def_value = (cs->which == V4L2_CTRL_WHICH_DEF_VAL);
 
        cs->error_idx = cs->count;
        cs->which = V4L2_CTRL_ID2WHICH(cs->which);
@@ -2829,9 +2845,11 @@ int v4l2_g_ext_ctrls(struct v4l2_ctrl_handler *hdl, struct v4l2_ext_controls *cs
 
        for (i = 0; !ret && i < cs->count; i++) {
                int (*ctrl_to_user)(struct v4l2_ext_control *c,
-                                   struct v4l2_ctrl *ctrl) = cur_to_user;
+                                   struct v4l2_ctrl *ctrl);
                struct v4l2_ctrl *master;
 
+               ctrl_to_user = def_value ? def_to_user : cur_to_user;
+
                if (helpers[i].mref == NULL)
                        continue;
 
@@ -2841,8 +2859,9 @@ int v4l2_g_ext_ctrls(struct v4l2_ctrl_handler *hdl, struct v4l2_ext_controls *cs
                v4l2_ctrl_lock(master);
 
                /* g_volatile_ctrl will update the new control values */
-               if ((master->flags & V4L2_CTRL_FLAG_VOLATILE) ||
-                       (master->has_volatiles && !is_cur_manual(master))) {
+               if (!def_value &&
+                   ((master->flags & V4L2_CTRL_FLAG_VOLATILE) ||
+                   (master->has_volatiles && !is_cur_manual(master)))) {
                        for (j = 0; j < master->ncontrols; j++)
                                cur_to_new(master->cluster[j]);
                        ret = call_op(master, g_volatile_ctrl);
@@ -3064,6 +3083,11 @@ static int try_set_ext_ctrls(struct v4l2_fh *fh, struct v4l2_ctrl_handler *hdl,
        int ret;
 
        cs->error_idx = cs->count;
+
+       /* Default value cannot be changed */
+       if (cs->which == V4L2_CTRL_WHICH_DEF_VAL)
+               return -EINVAL;
+
        cs->which = V4L2_CTRL_ID2WHICH(cs->which);
 
        if (hdl == NULL)