V4L/DVB (10544): v4l2-common: add comments warning that about the sort order

Control arrays as are used with v4l2_ctrl_next must be sorted from
low to high. Add a comment at the top of all such arrays to warn
about this.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/cx18/cx18-controls.c

@@ -30,6 +30,7 @@
 #include "cx18-mailbox.h"
 #include "cx18-controls.h"
 
+/* Must be sorted from low to high control ID! */
 static const u32 user_ctrls[] = {
 	V4L2_CID_USER_CLASS,
 	V4L2_CID_BRIGHTNESS,

drivers/media/video/cx2341x.c

@@ -38,6 +38,7 @@ static int debug;
 module_param(debug, int, 0644);
 MODULE_PARM_DESC(debug, "Debug level (0-1)");
 
+/* Must be sorted from low to high control ID! */
 const u32 cx2341x_mpeg_ctrls[] = {
 	V4L2_CID_MPEG_CLASS,
 	V4L2_CID_MPEG_STREAM_TYPE,

drivers/media/video/cx23885/cx23885-video.c

@@ -244,6 +244,7 @@ static struct cx23885_ctrl cx23885_ctls[] = {
 };
 static const int CX23885_CTLS = ARRAY_SIZE(cx23885_ctls);
 
+/* Must be sorted from low to high control ID! */
 static const u32 cx23885_user_ctrls[] = {
 	V4L2_CID_USER_CLASS,
 	V4L2_CID_BRIGHTNESS,

drivers/media/video/cx88/cx88-video.c

@@ -298,6 +298,7 @@ static struct cx88_ctrl cx8800_ctls[] = {
 };
 static const int CX8800_CTLS = ARRAY_SIZE(cx8800_ctls);
 
+/* Must be sorted from low to high control ID! */
 const u32 cx88_user_ctrls[] = {
 	V4L2_CID_USER_CLASS,
 	V4L2_CID_BRIGHTNESS,

drivers/media/video/ivtv/ivtv-controls.c

@@ -26,6 +26,7 @@
 #include "ivtv-mailbox.h"
 #include "ivtv-controls.h"
 
+/* Must be sorted from low to high control ID! */
 static const u32 user_ctrls[] = {
 	V4L2_CID_USER_CLASS,
 	V4L2_CID_BRIGHTNESS,

drivers/media/video/saa7134/saa7134-empress.c

@@ -352,6 +352,7 @@ static int empress_s_ctrl(struct file *file, void *priv,
 static int empress_queryctrl(struct file *file, void *priv,
 					struct v4l2_queryctrl *c)
 {
+	/* Must be sorted from low to high control ID! */
 	static const u32 user_ctrls[] = {
 		V4L2_CID_USER_CLASS,
 		V4L2_CID_BRIGHTNESS,
@@ -364,6 +365,7 @@ static int empress_queryctrl(struct file *file, void *priv,
 		0
 	};
 
+	/* Must be sorted from low to high control ID! */
 	static const u32 mpeg_ctrls[] = {
 		V4L2_CID_MPEG_CLASS,
 		V4L2_CID_MPEG_STREAM_TYPE,

drivers/media/video/v4l2-common.c

@@ -749,7 +749,7 @@ 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
-   class. The array of u32 pointer must also be sorted, from low class IDs
+   class. The array of u32 pointers must also be sorted, from low class IDs
    to high class IDs.
 
    This function returns the first ID that follows after the given ID.

include/media/v4l2-common.h

@@ -107,6 +107,11 @@ 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);
+
+/* Note: ctrl_classes points to an array of u32 pointers. 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 class. The array of u32 pointers must also
+   be sorted, from low class IDs to high class IDs. */
 u32 v4l2_ctrl_next(const u32 * const *ctrl_classes, u32 id);
 
 /* ------------------------------------------------------------------------- */