[PATCH v4 3/8] libcamera: uvcvideo: Register ExposureTimeMode control

[Laurent Pinchart]

Hi Paul,

Thank you for the patch.

On Thu, Dec 05, 2024 at 08:22:36PM +0900, Paul Elder wrote:
> From: Jacopo Mondi <jacopo at jmondi.org>
> 
> Port the UVC pipeline handler to use the new ExposureTimeMode control
> when processing Camera controls in place of the AeEnable control.
> 
> The V4L2_CID_EXPOSURE_AUTO control allows 4 possible values, which
> map to ExposureTimeModeAuto and ExposureTimeModeManual.
> 
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> Reviewed-by: Paul Elder <paul.elder at ideasonboard.com>

With have AGC-related issues in the UVC pipeline handler (see
https://bugs.libcamera.org/show_bug.cgi?id=242). This patch doesn't seem
to make the problem worse, so I'm fine with this. Just one comment
below.

> ---
> No change in v3
> ---
>  src/libcamera/pipeline/uvcvideo/uvcvideo.cpp | 54 ++++++++++++++++++--
>  1 file changed, 49 insertions(+), 5 deletions(-)
> 
> diff --git a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
> index 8c2c6baf3575..a2f0935181d4 100644
> --- a/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
> +++ b/src/libcamera/pipeline/uvcvideo/uvcvideo.cpp
> @@ -298,7 +298,7 @@ int PipelineHandlerUVC::processControl(ControlList *controls, unsigned int id,
>  		cid = V4L2_CID_CONTRAST;
>  	else if (id == controls::Saturation)
>  		cid = V4L2_CID_SATURATION;
> -	else if (id == controls::AeEnable)
> +	else if (id == controls::ExposureTimeMode)
>  		cid = V4L2_CID_EXPOSURE_AUTO;
>  	else if (id == controls::ExposureTime)
>  		cid = V4L2_CID_EXPOSURE_ABSOLUTE;
> @@ -647,7 +647,7 @@ void UVCCameraData::addControl(uint32_t cid, const ControlInfo &v4l2Info,
>  		id = &controls::Saturation;
>  		break;
>  	case V4L2_CID_EXPOSURE_AUTO:
> -		id = &controls::AeEnable;
> +		id = &controls::ExposureTimeMode;
>  		break;
>  	case V4L2_CID_EXPOSURE_ABSOLUTE:
>  		id = &controls::ExposureTime;
> @@ -660,6 +660,7 @@ void UVCCameraData::addControl(uint32_t cid, const ControlInfo &v4l2Info,
>  	}
>  
>  	/* Map the control info. */
> +	const std::vector<ControlValue> &v4l2Values = v4l2Info.values();
>  	int32_t min = v4l2Info.min().get<int32_t>();
>  	int32_t max = v4l2Info.max().get<int32_t>();
>  	int32_t def = v4l2Info.def().get<int32_t>();
> @@ -697,10 +698,53 @@ void UVCCameraData::addControl(uint32_t cid, const ControlInfo &v4l2Info,
>  		};
>  		break;
>  
> -	case V4L2_CID_EXPOSURE_AUTO:
> -		info = ControlInfo{ false, true, true };
> +	case V4L2_CID_EXPOSURE_AUTO: {
> +		/*
> +		 * From the V4L2_CID_EXPOSURE_AUTO documentation:
> +		 *
> +		 * ------------------------------------------------------------
> +		 * V4L2_EXPOSURE_AUTO:
> +		 * Automatic exposure time, automatic iris aperture.
> +		 *
> +		 * V4L2_EXPOSURE_MANUAL:
> +		 * Manual exposure time, manual iris.
> +		 *
> +		 * V4L2_EXPOSURE_SHUTTER_PRIORITY:
> +		 * Manual exposure time, auto iris.
> +		 *
> +		 * V4L2_EXPOSURE_APERTURE_PRIORITY:
> +		 * Auto exposure time, manual iris.
> +		 *-------------------------------------------------------------
> +		 *
> +		 * ExposureTimeModeAuto = { V4L2_EXPOSURE_AUTO,
> +		 * 			    V4L2_EXPOSURE_APERTURE_PRIORITY }
> +		 *
> +		 *
> +		 * ExposureTimeModeManual = { V4L2_EXPOSURE_MANUAL,
> +		 *			      V4L2_EXPOSURE_SHUTTER_PRIORITY }
> +		 */
> +		std::array<int32_t, 2> values{};
> +
> +		auto it = std::find_if(v4l2Values.begin(), v4l2Values.end(),
> +			[&](const ControlValue &val) {
> +				return (val.get<int32_t>() == V4L2_EXPOSURE_APERTURE_PRIORITY ||
> +					val.get<int32_t>() == V4L2_EXPOSURE_AUTO) ? true : false;
> +			});
> +		if (it != v4l2Values.end())
> +			values.back() = static_cast<int32_t>(controls::ExposureTimeModeAuto);
> +
> +		it = std::find_if(v4l2Values.begin(), v4l2Values.end(),
> +			[&](const ControlValue &val) {
> +				return (val.get<int32_t>() == V4L2_EXPOSURE_SHUTTER_PRIORITY ||
> +					val.get<int32_t>() == V4L2_EXPOSURE_MANUAL) ? true : false;
> +			});
> +		if (it != v4l2Values.end())
> +			values.back() = static_cast<int32_t>(controls::ExposureTimeModeManual);
> +
> +		int32_t *data = values.data();
> +		info = ControlInfo{Span<int32_t>(data, 2), values[0]};

You don't need the data variable, you can write

		info = ControlInfo{Span<int32_t>{values}, values[0]};

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

>  		break;
> -
> +	}
>  	case V4L2_CID_EXPOSURE_ABSOLUTE:
>  		/*
>  		 * ExposureTime is in units of 1 µs, and UVC expects

-- 
Regards,

Laurent Pinchart