V4L/DVB (8637): v4l2: add v4l2_ctrl_query_menu_valid_items support function

v4l2_ctrl_query_menu_valid_items() makes it easy to handle control menus
that have a lot of invalid 'holes'. For example, many MPEG encoders only
support a limited subset of audio bitrates. In that case a driver can
specify an array listing the set of valid bitrates and pass that to
this function.
Signed-off-by: NHans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/v4l2-common.c

@@ -643,6 +643,7 @@ int v4l2_ctrl_query_menu(struct v4l2_querymenu *qmenu, struct v4l2_queryctrl *qc
 {
 	int i;
 
+	qmenu->reserved = 0;
 	if (menu_items == NULL ||
 	    (qctrl && (qmenu->index < qctrl->minimum || qmenu->index > qctrl->maximum)))
 		return -EINVAL;
@@ -650,11 +651,31 @@ int v4l2_ctrl_query_menu(struct v4l2_querymenu *qmenu, struct v4l2_queryctrl *qc
 	if (menu_items[i] == NULL || menu_items[i][0] == '\0')
 		return -EINVAL;
 	snprintf(qmenu->name, sizeof(qmenu->name), menu_items[qmenu->index]);
-	qmenu->reserved = 0;
 	return 0;
 }
 EXPORT_SYMBOL(v4l2_ctrl_query_menu);
 
+/* Fill in a struct v4l2_querymenu based on the specified array of valid
+   menu items (terminated by V4L2_CTRL_MENU_IDS_END).
+   Use this if there are 'holes' in the list of valid menu items. */
+int v4l2_ctrl_query_menu_valid_items(struct v4l2_querymenu *qmenu, const u32 *ids)
+{
+	const char **menu_items = v4l2_ctrl_get_menu(qmenu->id);
+
+	qmenu->reserved = 0;
+	if (menu_items == NULL || ids == NULL)
+		return -EINVAL;
+	while (*ids != V4L2_CTRL_MENU_IDS_END) {
+		if (*ids++ == qmenu->index) {
+			snprintf(qmenu->name, sizeof(qmenu->name),
+				       menu_items[qmenu->index]);
+			return 0;
+		}
+	}
+	return -EINVAL;
+}
+EXPORT_SYMBOL(v4l2_ctrl_query_menu_valid_items);
+
 /* ctrl_classes points to an array of u32 pointers, the last element is
    a NULL pointer. Each u32 array is a 0-terminated array of control IDs.
    Each array must be sorted low to high and belong to the same control

include/media/v4l2-common.h

@@ -82,6 +82,8 @@ int v4l2_ctrl_query_fill(struct v4l2_queryctrl *qctrl, s32 min, s32 max, s32 ste
 int v4l2_ctrl_query_fill_std(struct v4l2_queryctrl *qctrl);
 int v4l2_ctrl_query_menu(struct v4l2_querymenu *qmenu,
 		struct v4l2_queryctrl *qctrl, const char **menu_items);
+#define V4L2_CTRL_MENU_IDS_END (0xffffffff)
+int v4l2_ctrl_query_menu_valid_items(struct v4l2_querymenu *qmenu, const u32 *ids);
 u32 v4l2_ctrl_next(const u32 * const *ctrl_classes, u32 id);
 
 /* ------------------------------------------------------------------------- */