[libcamera-devel] [PATCH v6 2/6] libcamera: V4L2Device: Support v4l2 menu control

[Laurent Pinchart]

Hi Hiro,

On Mon, Jun 07, 2021 at 09:14:21AM +0900, Hirokazu Honda wrote:
> On Mon, Jun 7, 2021 at 8:22 AM Laurent Pinchart wrote:
> > On Fri, May 28, 2021 at 12:05:27PM +0900, Hirokazu Honda wrote:
> > > This adds a support of v4l2 menu. The control info for v4l2 menu
> > > contains indices without names and 64bit values of querymenu.
> > >
> > > Signed-off-by: Hirokazu Honda <hiroh at chromium.org>
> > > ---
> > >  include/libcamera/internal/v4l2_device.h |  2 +
> > >  src/libcamera/v4l2_device.cpp            | 47 ++++++++++++++++++++++--
> > >  2 files changed, 45 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/include/libcamera/internal/v4l2_device.h b/include/libcamera/internal/v4l2_device.h
> > > index b82e2a14..687be9b2 100644
> > > --- a/include/libcamera/internal/v4l2_device.h
> > > +++ b/include/libcamera/internal/v4l2_device.h
> > > @@ -56,6 +56,8 @@ protected:
> > >       int fd() const { return fd_; }
> > >
> > >  private:
> > > +     ControlInfo v4l2MenuControlInfo(const v4l2_query_ext_ctrl &ctrl);
> > > +
> > >       void listControls();
> > >       void updateControls(ControlList *ctrls,
> > >                           Span<const v4l2_ext_control> v4l2Ctrls);
> > > diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> > > index caafbc2d..032252bb 100644
> > > --- a/src/libcamera/v4l2_device.cpp
> > > +++ b/src/libcamera/v4l2_device.cpp
> > > @@ -530,6 +530,33 @@ int V4L2Device::ioctl(unsigned long request, void *argp)
> > >   * \return The V4L2 device file descriptor, -1 if the device node is not open
> > >   */
> > >
> > > +/**
> > > + * \brief Create ControlInfo for v4l2 menu ctrl
> >
> > s/for v4l2 menu ctrl/for a V4L2 menu control/
> >
> > > + * \param[in] ctrl The v4l2_query_ext_ctrl that represents a menu
> > > + * \param[out] ctrlInfo The created controlInfo
> >
> > It's not an out parameter, it's the return value.
> >
> > > + *
> > > + * The created ControlInfo contains indices acquired by VIDIOC_QUERYMENU.
> > > + *
> > > + * \return ControlInfo for v4l2 menu ctrl.
> > > + */
> > > +ControlInfo V4L2Device::v4l2MenuControlInfo(const v4l2_query_ext_ctrl &ctrl)
> > > +{
> > > +     std::vector<ControlValue> indices;
> > > +     v4l2_querymenu menu;
> >
> > We usually prefix the V4L2 structures with struct. While not strictly
> > mandatory, it emphasizes that there are C structs from V4L2.
> >
> > > +     memset(&menu, 0, sizeof(menu));
> >
> > You could also write this
> >
> >         struct v4l2_querymenu menu = { };
> >
> > (I really wish designated initializers were available before C++20 :-().
> >
> > > +     menu.id = ctrl.id;
> >
> > As a sanity check, should we add
> >
> >         if (ctrl.minimum <= 0)
> >                 return ControlInfo();
> >
> > ?
> >
> > > +
> > > +     for (menu.index = ctrl.minimum;
> > > +          static_cast<int32_t>(menu.index) <= ctrl.maximum; menu.index++) {
> >
> >         for (int32_t index = ctrl.minimum; index <= ctrl.maximum; ++index)
> > }
> >                 menu.index = index;
> >
> > would allow dropping the cast. Up to you.
> >
> > > +             if (ioctl(VIDIOC_QUERYMENU, &menu) != 0)
> > > +                     continue;
> > > +
> > > +             indices.emplace_back(static_cast<int32_t>(menu.index));
> >
> > This could be
> >
> >                 indices.emplace_back(index);
> >
> > or even
> >
> >                 indices.push_back(index);
> >
> > as it won't make much of a difference.
> >
> > > +     }
> > > +
> > > +     return ControlInfo(indices);
> >
> > Would it be useful to also pass the default value to the ControlInfo
> > constructor ?
>
> You mean, I should set ctrl.default_value or some value in indices like
> indices.begin()?

I mean (untested)

	return ControlInfo(indices, ControlValue<int32_t>(ctrl.dev));

> > > +}
> > > +
> > >  /*
> > >   * \brief List and store information about all controls supported by the
> > >   * V4L2 device
> > > @@ -539,7 +566,6 @@ void V4L2Device::listControls()
> > >       ControlInfoMap::Map ctrls;
> > >       struct v4l2_query_ext_ctrl ctrl = {};
> > >
> > > -     /* \todo Add support for menu controls. */
> > >       while (1) {
> > >               ctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL |
> > >                          V4L2_CTRL_FLAG_NEXT_COMPOUND;
> > > @@ -550,16 +576,22 @@ void V4L2Device::listControls()
> > >                   ctrl.flags & V4L2_CTRL_FLAG_DISABLED)
> > >                       continue;
> > >
> > > +             ControlInfo ctrlInfo;
> >
> > I'd add a blank line here.
> >
> > >               switch (ctrl.type) {
> > >               case V4L2_CTRL_TYPE_INTEGER:
> > >               case V4L2_CTRL_TYPE_BOOLEAN:
> > > -             case V4L2_CTRL_TYPE_MENU:
> > >               case V4L2_CTRL_TYPE_BUTTON:
> > >               case V4L2_CTRL_TYPE_INTEGER64:
> > >               case V4L2_CTRL_TYPE_BITMASK:
> > > -             case V4L2_CTRL_TYPE_INTEGER_MENU:
> > >               case V4L2_CTRL_TYPE_U8:
> > > +                     ctrlInfo = v4l2ControlInfo(ctrl);
> > > +                     break;
> > > +
> > > +             case V4L2_CTRL_TYPE_INTEGER_MENU:
> > > +             case V4L2_CTRL_TYPE_MENU:
> > > +                     ctrlInfo = v4l2MenuControlInfo(ctrl);
> > >                       break;
> > > +
> > >               /* \todo Support other control types. */
> > >               default:
> > >                       LOG(V4L2, Debug)
> > > @@ -568,10 +600,13 @@ void V4L2Device::listControls()
> > >                       continue;
> > >               }
> > >
> > > +             LOG(V4L2, Debug) << "Control: " << ctrl.name
> > > +                              << " (" << utils::hex(ctrl.id) << ")";
> > > +
> > >               controlIds_.emplace_back(v4l2ControlId(ctrl));
> > >               controlInfo_.emplace(ctrl.id, ctrl);
> > >
> > > -             ctrls.emplace(controlIds_.back().get(), v4l2ControlInfo(ctrl));
> > > +             ctrls.emplace(controlIds_.back().get(), std::move(ctrlInfo));
> > >       }
> > >
> > >       controls_ = std::move(ctrls);
> > > @@ -638,6 +673,10 @@ void V4L2Device::updateControls(ControlList *ctrls,
> > >                       value.set<int64_t>(v4l2Ctrl->value64);
> > >                       break;
> > >
> > > +             case ControlTypeInteger32:
> > > +                     value.set<int32_t>(v4l2Ctrl->value);
> >
> > This needs a rebase, it's now v4l2Ctrl.value.
> 
> By which patch? On top of tree, v4l2Ctrl is still a const pointer.

By commit abdb11d9ccad ("libcamera: V4L2Device: Remove the controls
order assumption in updateControls()")  :-)

> > With these minor issues addressed, the patch looks good to me. Thanks
> > for your continuous effort.
> >
> > > +                     break;
> > > +
> > >               case ControlTypeByte:
> > >                       /*
> > >                        * No action required, the VIDIOC_[GS]_EXT_CTRLS ioctl

-- 
Regards,

Laurent Pinchart