[PATCH] libcamera: Add open() and close() in CameraLens

[Laurent Pinchart]

CC'ing Sakari.

On Sat, Oct 19, 2024 at 11:32:02PM +0100, Kieran Bingham wrote:
> Quoting Harvey Yang (2024-10-17 08:39:47)
> > From: Han-Lin Chen <hanlinchen at chromium.org>
> > 
> > This allows pipeline handlers to save some power when a camera is close.
> 
> This seems reasonable - but makes me wonder - is there similar
> limitations with the CameraSensor class that has a very similar design?

I think it's time to bite the bullet and see how to address the issue of
power management of lens controllers in the kernel. Tying it to open()
and close() isn't necessarily a great option.

> > Signed-off-by: Han-Lin Chen <hanlinchen at chromium.org>
> > Co-developed-by: Harvey Yang <chenghaoyang at chromium.org>
> > Signed-off-by: Harvey Yang <chenghaoyang at chromium.org>
> > ---
> >  include/libcamera/internal/camera_lens.h |  4 ++++
> >  src/libcamera/camera_lens.cpp            | 17 +++++++++++++++++
> >  2 files changed, 21 insertions(+)
> > 
> > diff --git a/include/libcamera/internal/camera_lens.h b/include/libcamera/internal/camera_lens.h
> > index 5a4b993bb..095056791 100644
> > --- a/include/libcamera/internal/camera_lens.h
> > +++ b/include/libcamera/internal/camera_lens.h
> > @@ -26,6 +26,10 @@ public:
> >         ~CameraLens();
> >  
> >         int init();
> 
> Should we be calling close() at the end of init()? Perhaps with some
> sort of way to make sure if an API call is used on a now closed device
> it gets opened again first ? (i.e. mostly perhaps V4L2Device::setControls)?
> 
> > +
> > +       int open();
> > +       void close();
> > +
> >         int setFocusPosition(int32_t position);
> >  
> >         const std::string &model() const { return model_; }
> > diff --git a/src/libcamera/camera_lens.cpp b/src/libcamera/camera_lens.cpp
> > index ccc2a6a65..039f5ad2a 100644
> > --- a/src/libcamera/camera_lens.cpp
> > +++ b/src/libcamera/camera_lens.cpp
> > @@ -76,6 +76,23 @@ int CameraLens::init()
> >         return 0;
> >  }
> >  
> > +/**
> > + * \brief Open the subdev
> > + * \return 0 on success or a negative error code otherwise
> > + */
> > +int CameraLens::open()
> > +{
> > +       return subdev_->open();
> > +}
> > +
> > +/**
> > + * \brief Close the subdev
> > + */
> > +void CameraLens::close()
> > +{
> > +       subdev_->close();
> > +}
> > +
> >  /**
> >   * \brief This function sets the focal point of the lens to a specific position.
> >   * \param[in] position The focal point of the lens

-- 
Regards,

Laurent Pinchart