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SubjectRe: [PATCH v2] media: v4l2-ctrls: add control for test pattern
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Hi Sakari,

On Sunday 09 September 2012 10:40:17 Sakari Ailus wrote:
> On Sat, Sep 08, 2012 at 01:11:04PM +0200, Hans Verkuil wrote:
> > On Fri September 7 2012 20:20:51 Sakari Ailus wrote:
> > > Prabhakar Lad wrote:
> > > > From: Lad, Prabhakar <prabhakar.lad@ti.com>
> > > >
> > > > add V4L2_CID_TEST_PATTERN of type menu, which determines
> > > > the internal test pattern selected by the device.
> > > >
> > > > Signed-off-by: Lad, Prabhakar <prabhakar.lad@ti.com>
> > > > Signed-off-by: Manjunath Hadli <manjunath.hadli@ti.com>
> > > > Cc: Sakari Ailus <sakari.ailus@iki.fi>
> > > > Cc: Hans Verkuil <hans.verkuil@cisco.com>
> > > > Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> > > > Cc: Mauro Carvalho Chehab <mchehab@infradead.org>
> > > > Cc: Sylwester Nawrocki <s.nawrocki@samsung.com>
> > > > Cc: Hans de Goede <hdegoede@redhat.com>
> > > > Cc: Kyungmin Park <kyungmin.park@samsung.com>
> > > > Cc: Rob Landley <rob@landley.net>
> > > > ---
> > > > This patches has one checkpatch warning for line over
> > > > 80 characters altough it can be avoided I have kept it
> > > > for consistency.
> > > >
> > > > Changes for v2:
> > > > 1: Included display devices in the description for test pattern
> > > > as pointed by Hans.
> > > >
> > > > 2: In the menu replaced 'Test Pattern Disabled' by 'Disabled' as
> > > > pointed by Sylwester.
> > > >
> > > > 3: Removed the test patterns from menu as the are hardware specific
> > > > as pointed by Sakari.
> > > >
> > > > Documentation/DocBook/media/v4l/controls.xml | 20 ++++++++++++++++
> > > > drivers/media/v4l2-core/v4l2-ctrls.c | 8 ++++++++
> > > > include/linux/videodev2.h | 4 ++++
> > > > 3 files changed, 32 insertions(+), 0 deletions(-)
> > > >
> > > > diff --git a/Documentation/DocBook/media/v4l/controls.xml
> > > > b/Documentation/DocBook/media/v4l/controls.xml index ad873ea..173934e
> > > > 100644
> > > > --- a/Documentation/DocBook/media/v4l/controls.xml
> > > > +++ b/Documentation/DocBook/media/v4l/controls.xml
> > > > @@ -4311,6 +4311,26 @@ interface and may change in the future.</para>
> > > > </tbody>
> > > > </entrytbl>
> > > > </row>
> > > > + <row>
> > > > + <entry
> > > > spanname="id"><constant>V4L2_CID_TEST_PATTERN</constant></entry> +
> > > > <entry>menu</entry>
> > > > + </row>
> > > > + <row id="v4l2-test-pattern">
> > > > + <entry spanname="descr"> The Capture/Display/Sensors have the
> > > > capability
> > > > + to generate internal test patterns and this are hardware
> > > > specific. This
> > > > + test patterns are used to test a device is properly working and
> > > > can generate
> > > > + the desired waveforms that
> > > > it supports.</entry>
> > > > + </row>
> > > > + <row>
> > > > + <entrytbl spanname="descr" cols="2">
> > > > + <tbody valign="top">
> > > > + <row>
> > > > +
> > > > <entry><constant>V4L2_TEST_PATTERN_DISABLED</constant></entry>
> > > > + <entry>Test pattern generation is disabled</entry>
> > > > + </row>
> > > > + </tbody>
> > > > + </entrytbl>
> > > > + </row>
> > > > <row><entry></entry></row>
> > > > </tbody>
> > > > </tgroup>
> > > > diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c
> > > > b/drivers/media/v4l2-core/v4l2-ctrls.c index 8f2f40b..d731422 100644
> > > > --- a/drivers/media/v4l2-core/v4l2-ctrls.c
> > > > +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
> > > > @@ -430,6 +430,10 @@ const char * const *v4l2_ctrl_get_menu(u32 id)
> > > > "Advanced",
> > > > NULL,
> > > > };
> > > > + static const char * const test_pattern[] = {
> > > > + "Disabled",
> > > > + NULL,
> > > > + };
> > > >
> > > > switch (id) {
> > > > case V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ:
> > > > @@ -509,6 +513,8 @@ const char * const *v4l2_ctrl_get_menu(u32 id)
> > > > return jpeg_chroma_subsampling;
> > > > case V4L2_CID_DPCM_PREDICTOR:
> > > > return dpcm_predictor;
> > > > + case V4L2_CID_TEST_PATTERN:
> > > > + return test_pattern;
> > >
> > > I think it's not necessary to define test_pattern (nor be prepared to
> > > return it) since the menu is going to be device specific. So the driver
> > > is responsible for all of the menu items. Such menus are created using
> > > v4l2_ctrl_new_custom() instead of v4l2_ctrl_new_std_menu().
> > >
> > > Looks good to me otherwise.
> >
> > I would suggest that we *do* make this a standard control, but the menu
> > consists of just one item: "Disabled". After creating the control you can
> > just set the ctrl->qmenu pointer to the device-specific menu. I like
> > using standard controls because they guarantee standard naming and type
> > conventions. They are also easier to use in an application.
>
> That's not quite enough. Also menu_skip_mask and max also need to be
> replaced. In a general case min as well. It's easy to do mistakes in that
> --- how about a separate function for doing that? It'd be also nice to be
> able to use the existing standardised menu item strings, but that's just an
> extra plus.

Agreed. A way to create a standard menu control with driver-supplied menu
items would be a good addition to the control framework API.

> However I think it's beyond this patch, which I think then is be fine w/o
> modifications. So on my behalf,
>
> Acked-by: Sakari Ailus <sakari.ailus@iki.fi>

--
Regards,

Laurent Pinchart



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