From: Lad, Prabhakar <prabhakar....@ti.com>

Add a helper function to modify the menu, max and default value
to set.

Signed-off-by: Lad, Prabhakar <prabhakar....@ti.com>
Signed-off-by: Manjunath Hadli <manjunath.ha...@ti.com>
Cc: Hans Verkuil <hans.verk...@cisco.com>
Cc: Sakari Ailus <sakari.ai...@iki.fi>
Cc: Sylwester Nawrocki <s.nawro...@samsung.com>
Cc: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
Cc: Mauro Carvalho Chehab <mche...@infradead.org>
Cc: Hans de Goede <hdego...@redhat.com>
Cc: Kyungmin Park <kyungmin.p...@samsung.com>
Cc: Guennadi Liakhovetski <g.liakhovet...@gmx.de>
Cc: Rob Landley <r...@landley.net>
---
Changes for v3:
1: Fixed style/grammer issues as pointed by Hans.
   Thanks Hans for providing the description.

Changes for v2:
1: Fixed review comments from Hans, to have return type as
   void, add WARN_ON() for fail conditions, allow this fucntion
   to modify the menu of custom controls.

 Documentation/video4linux/v4l2-controls.txt |   29 +++++++++++++++++++++++++++
 drivers/media/v4l2-core/v4l2-ctrls.c        |   17 +++++++++++++++
 include/media/v4l2-ctrls.h                  |   11 ++++++++++
 3 files changed, 57 insertions(+), 0 deletions(-)

diff --git a/Documentation/video4linux/v4l2-controls.txt 
b/Documentation/video4linux/v4l2-controls.txt
index 43da22b..01d0a82 100644
--- a/Documentation/video4linux/v4l2-controls.txt
+++ b/Documentation/video4linux/v4l2-controls.txt
@@ -367,6 +367,35 @@ it to 0 means that all menu items are supported.
 You set this mask either through the v4l2_ctrl_config struct for a custom
 control, or by calling v4l2_ctrl_new_std_menu().
 
+There are situations where menu items may be device specific. In such cases the
+framework provides a helper function to change the menu:
+
+void v4l2_ctrl_modify_menu(struct v4l2_ctrl *ctrl, const char * const *qmenu,
+       s32 max, u32 menu_skip_mask, s32 def);
+
+A good example 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.
+
+This helper function is used to modify the menu, max, mask and the default
+value of the control.
+
+Example:
+
+       static const char * const test_pattern[] = {
+               "Disabled",
+               "Vertical Bars",
+               "Solid Black",
+               "Solid White",
+               NULL,
+       };
+       struct v4l2_ctrl *test_pattern_ctrl =
+               v4l2_ctrl_new_std_menu(&foo->ctrl_handler, &foo_ctrl_ops,
+                       V4L2_CID_TEST_PATTERN, V4L2_TEST_PATTERN_DISABLED, 0,
+                       V4L2_TEST_PATTERN_DISABLED);
+
+       v4l2_ctrl_modify_menu(test_pattern_ctrl, test_pattern, 3, 0,
+               V4L2_TEST_PATTERN_DISABLED);
 
 Custom Controls
 ===============
diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c 
b/drivers/media/v4l2-core/v4l2-ctrls.c
index d731422..d89b460 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls.c
@@ -2666,3 +2666,20 @@ unsigned int v4l2_ctrl_poll(struct file *file, struct 
poll_table_struct *wait)
        return 0;
 }
 EXPORT_SYMBOL(v4l2_ctrl_poll);
+
+/* Helper function for modifying the menu */
+void v4l2_ctrl_modify_menu(struct v4l2_ctrl *ctrl, const char * const *qmenu,
+                          s32 max, u32 menu_skip_mask, s32 def)
+{
+       if (WARN_ON(ctrl->type != V4L2_CTRL_TYPE_MENU || qmenu == NULL))
+               return;
+
+       if (WARN_ON(def < 0 || def > max))
+               return;
+
+       ctrl->qmenu = qmenu;
+       ctrl->maximum = max;
+       ctrl->menu_skip_mask = menu_skip_mask;
+       ctrl->cur.val = ctrl->val = ctrl->default_value = def;
+}
+EXPORT_SYMBOL(v4l2_ctrl_modify_menu);
diff --git a/include/media/v4l2-ctrls.h b/include/media/v4l2-ctrls.h
index 776605f..5303489 100644
--- a/include/media/v4l2-ctrls.h
+++ b/include/media/v4l2-ctrls.h
@@ -488,6 +488,17 @@ static inline void v4l2_ctrl_unlock(struct v4l2_ctrl *ctrl)
        mutex_unlock(ctrl->handler->lock);
 }
 
+/**
+ * v4l2_ctrl_modify_menu() - This function is used to modify the menu.
+ * @ctrl:              The control whose menu should be modified.
+ * @qmenu:             The new menu.
+ * @max:               Maximum value of the control.
+ * @menu_skip_mask:    The control's skip mask for menu controls.
+ * @def:               The default value for control to be set.
+ */
+void v4l2_ctrl_modify_menu(struct v4l2_ctrl *ctrl, const char * const *qmenu,
+                          s32 max, u32 menu_skip_mask, s32 def);
+
 /** v4l2_ctrl_g_ctrl() - Helper function to get the control's value from 
within a driver.
   * @ctrl:     The control.
   *
-- 
1.7.0.4

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