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-rw-r--r--Documentation/video4linux/v4l2-controls.txt30
1 files changed, 29 insertions, 1 deletions
diff --git a/Documentation/video4linux/v4l2-controls.txt b/Documentation/video4linux/v4l2-controls.txt
index 43da22b..cfe52c7 100644
--- a/Documentation/video4linux/v4l2-controls.txt
+++ b/Documentation/video4linux/v4l2-controls.txt
@@ -136,11 +136,25 @@ Or alternatively for integer menu controls, by calling v4l2_ctrl_new_int_menu:
const struct v4l2_ctrl_ops *ops,
u32 id, s32 max, s32 def, const s64 *qmenu_int);
+Standard menu controls with a driver specific menu are added by calling
+v4l2_ctrl_new_std_menu_items:
+
+ struct v4l2_ctrl *v4l2_ctrl_new_std_menu_items(
+ struct v4l2_ctrl_handler *hdl,
+ const struct v4l2_ctrl_ops *ops, u32 id, s32 max,
+ s32 skip_mask, s32 def, const char * const *qmenu);
+
These functions are typically called right after the v4l2_ctrl_handler_init:
static const s64 exp_bias_qmenu[] = {
-2, -1, 0, 1, 2
};
+ static const char * const test_pattern[] = {
+ "Disabled",
+ "Vertical Bars",
+ "Solid Black",
+ "Solid White",
+ };
v4l2_ctrl_handler_init(&foo->ctrl_handler, nr_of_controls);
v4l2_ctrl_new_std(&foo->ctrl_handler, &foo_ctrl_ops,
@@ -156,6 +170,9 @@ These functions are typically called right after the v4l2_ctrl_handler_init:
ARRAY_SIZE(exp_bias_qmenu) - 1,
ARRAY_SIZE(exp_bias_qmenu) / 2 - 1,
exp_bias_qmenu);
+ v4l2_ctrl_new_std_menu_items(&foo->ctrl_handler, &foo_ctrl_ops,
+ V4L2_CID_TEST_PATTERN, ARRAY_SIZE(test_pattern) - 1, 0,
+ 0, test_pattern);
...
if (foo->ctrl_handler.error) {
int err = foo->ctrl_handler.error;
@@ -185,6 +202,13 @@ v4l2_ctrl_new_std_menu in that it doesn't have the mask argument and takes
as the last argument an array of signed 64-bit integers that form an exact
menu item list.
+The v4l2_ctrl_new_std_menu_items function is very similar to
+v4l2_ctrl_new_std_menu but takes an extra parameter qmenu, which is the driver
+specific menu for an otherwise standard menu control. A good example for this
+control is the test pattern control for capture/display/sensors devices that
+have the capability to generate test patterns. These test patterns are hardware
+specific, so the contents of the menu will vary from device to device.
+
Note that if something fails, the function will return NULL or an error and
set ctrl_handler->error to the error code. If ctrl_handler->error was already
set, then it will just return and do nothing. This is also true for
@@ -594,7 +618,11 @@ handler and finally add the first handler to the second. For example:
v4l2_ctrl_new_std(&radio_ctrl_handler, &radio_ops, V4L2_CID_AUDIO_MUTE, ...);
v4l2_ctrl_new_std(&video_ctrl_handler, &video_ops, V4L2_CID_BRIGHTNESS, ...);
v4l2_ctrl_new_std(&video_ctrl_handler, &video_ops, V4L2_CID_CONTRAST, ...);
- v4l2_ctrl_add_handler(&video_ctrl_handler, &radio_ctrl_handler);
+ v4l2_ctrl_add_handler(&video_ctrl_handler, &radio_ctrl_handler, NULL);
+
+The last argument to v4l2_ctrl_add_handler() is a filter function that allows
+you to filter which controls will be added. Set it to NULL if you want to add
+all controls.
Or you can add specific controls to a handler: