[libcamera-devel] [RFC v1 2/5] libcamera: camera_lens: Get maximum VCM steps

[Jacopo Mondi]

Hi Kate,

On Thu, Apr 14, 2022 at 03:43:39PM +0800, Kate Hsuan via libcamera-devel wrote:
> It allows other components to get the maximum VCM steps. It first creates
> a control list and set V4L2_CID_FOCUS_ABSOLUTE control to it. Then, it
> calls a lower layer call, getAttributes() to get the maximum VCM steps
> from the kernel.

I might have missed something here.

V4L2Device::controls() returns you a ControlInfoMap for all the
controls registered on the lens subdevice, with the controls' min, max
and default values collected at subdev open time with
V4L2Device::listControls()

Is there a reason I have missed about why you need to re-fetch the
control's limits again ?

If you need to collect the V4L2_CID_FOCUS_ABSOLUTE control maximum
value I think you could very well do so at validateLensDriver() time.

Thanks
   j

>
> Signed-off-by: Kate Hsuan<hpa at redhat.com>
> ---
>  include/libcamera/internal/camera_lens.h |  1 +
>  src/libcamera/camera_lens.cpp            | 18 ++++++++++++++++++
>  2 files changed, 19 insertions(+)
>
> diff --git a/include/libcamera/internal/camera_lens.h b/include/libcamera/internal/camera_lens.h
> index 277417da..48761d68 100644
> --- a/include/libcamera/internal/camera_lens.h
> +++ b/include/libcamera/internal/camera_lens.h
> @@ -27,6 +27,7 @@ public:
>
>  	int init();
>  	int setFocusPosition(int32_t position);
> +	int getFocusCapabilityies();
>
>  	const std::string &model() const { return model_; }
>
> diff --git a/src/libcamera/camera_lens.cpp b/src/libcamera/camera_lens.cpp
> index b3d48199..5d00652d 100644
> --- a/src/libcamera/camera_lens.cpp
> +++ b/src/libcamera/camera_lens.cpp
> @@ -73,6 +73,10 @@ int CameraLens::init()
>  		return ret;
>
>  	model_ = subdev_->model();
> +
> +	ControlList lensCtrls(subdev_->controls());
> +	subdev_->getAttributes(&lensCtrls);
> +
>  	return 0;
>  }
>
> @@ -95,6 +99,20 @@ int CameraLens::setFocusPosition(int32_t position)
>  	return 0;
>  }
>
> +int CameraLens::getFocusCapabilityies()
> +{
> +	ControlValue retVal;
> +	ControlList lensCtrls(subdev_->controls());
> +	int32_t ret = 2023;
> +
> +	lensCtrls.set(V4L2_CID_FOCUS_ABSOLUTE, static_cast<int32_t>(ret));
> +	subdev_->getAttributes(&lensCtrls);
> +	retVal = lensCtrls.get(V4L2_CID_FOCUS_ABSOLUTE);
> +	ret = retVal.get<int32_t>();
> +
> +	return ret;
> +}
> +
>  int CameraLens::validateLensDriver()
>  {
>  	int ret = 0;
> --
> 2.35.1
>