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SubjectRe: [PATCH v3] media: v4l2-ctrl: add a helper function to modify the menu
Date
On Thu 13 September 2012 13:43:36 Prabhakar Lad wrote:
> Hi Laurent,
>
> Thanks for the review.
>
> On Thursday 13 September 2012 06:45 AM, Laurent Pinchart wrote:
> > Hi Prabhakar,
> >
> > Thanks for the patch.
> >
> > On Tuesday 11 September 2012 19:53:38 Prabhakar Lad wrote:
> >> From: Lad, Prabhakar <prabhakar.lad@ti.com>
> >>
> >> Add a helper function to modify the menu, max and default value
> >> to set.
> >>
> >> Signed-off-by: Lad, Prabhakar <prabhakar.lad@ti.com>
> >> Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
> >> Cc: Hans Verkuil <hans.verkuil@cisco.com>
> >> Cc: Sakari Ailus <sakari.ailus@iki.fi>
> >> Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
> >> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> >> Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
> >> Cc: Hans de Goede <hdegoede@redhat.com>
> >> Cc: Kyungmin Park <kyungmin.park@samsung.com>
> >> Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> >> Cc: Rob Landley <rob@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);
> >
> > Sorry if this is a stupid question, but wouldn't it be better to add a
> > function to create a custom menu instead of modifying it afterwards ?
> >
> Create a custom menu? eventually everything boils down to modifying the
> menu itself.

Laurent, the reason we went for modifying a standard control is that that
ensures that the control name and type is all standardized. The only thing
that can be changed later is the menu contents.

Regards,

Hans

>
> Regards,
> --Prabhakar Lad
>
> >> +
> >> +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
> >> ===============
> >
>
>


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