[libcamera-devel] [PATCH v2] android: Check exposure time range for manual sensor capability

[Jean-Michel Hautbois]

Hi Paul,

Thanks for the patch !

On 18/11/2021 10:48, Paul Elder wrote:
> In the manual sensor capability validator, add a check for the exposure
> time range. While at it, since the minimum exposure time is not limited
> to the manual sensor capability, add a check for it when initializing
> static metadata.
> 
> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> 
> ---
> Changes in v2:
> - fix comparator order (cosmetic)
> - change comparators and comments to "equal or", as that is what is
>    specificied in the hal docs
> - add check for minimum exposure time when initializing static metadata
>    - this only prints error, should we return -EINVAL instead?
> ---
>   src/android/camera_capabilities.cpp | 30 +++++++++++++++++++++++++++++
>   1 file changed, 30 insertions(+)
> 
> diff --git a/src/android/camera_capabilities.cpp b/src/android/camera_capabilities.cpp
> index f357902e..6e46f163 100644
> --- a/src/android/camera_capabilities.cpp
> +++ b/src/android/camera_capabilities.cpp
> @@ -217,6 +217,8 @@ std::vector<U> setMetadata(CameraMetadata *metadata, uint32_t tag,
>   
>   bool CameraCapabilities::validateManualSensorCapability()
>   {
> +	camera_metadata_ro_entry_t entry;
> +
>   	const char *noMode = "Manual sensor capability unavailable: ";
>   
>   	if (!staticMetadata_->entryContains<uint8_t>(ANDROID_CONTROL_AE_AVAILABLE_MODES,
> @@ -231,6 +233,26 @@ bool CameraCapabilities::validateManualSensorCapability()
>   		return false;
>   	}
>   
> +	if (!staticMetadata_->hasEntry(ANDROID_SENSOR_INFO_EXPOSURE_TIME_RANGE)) {
> +		LOG(HAL, Info) << noMode << "missing exposure time range";
> +		return false;
> +	}
> +
> +	staticMetadata_->getEntry(ANDROID_SENSOR_INFO_EXPOSURE_TIME_RANGE, &entry);
> +	if (entry.data.i32[0] >= 100000) {
> +		LOG(HAL, Info)
> +			<< noMode
> +			<< "exposure time range minimum must not be equal nor larger than 100us";
> +		return false;
> +	}
> +
> +	if (entry.data.i32[1] <= 100000000) {
> +		LOG(HAL, Info)
> +			<< noMode
> +			<< "exposure time range maximum must not be equal nor smaller than 100ms";
> +		return false;
> +	}
> +
>   	/*
>   	 * \todo Return true here after we satisfy all the requirements:
>   	 * https://developer.android.com/reference/android/hardware/camera2/CameraMetadata#REQUEST_AVAILABLE_CAPABILITIES_MANUAL_SENSOR
> @@ -1074,6 +1096,14 @@ int CameraCapabilities::initializeStaticMetadata()
>   			exposureInfo->second.min().get<int32_t>() * 1000LL,
>   			exposureInfo->second.max().get<int32_t>() * 1000LL,
>   		};
> +
> +		if (exposureTimeRange[0] >= 100000) {
> +			LOG(HAL, Error)
> +				<< "Minimum exposure time "
> +				<< exposureTimeRange[0]
> +				<< "ns is too big (should be smaller than 100us)";
> +		}

I read the doc (better now than never :-)) in 
https://developer.android.com/reference/android/hardware/camera2/CameraCharacteristics#SENSOR_INFO_EXPOSURE_TIME_RANGE

Interestingly, the ExposureTimeRange is in nanoseconds. Our 
Controls::ExposureTime metadata is in microseconds. Should it be changed ?

Reviewed-by: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>

> +
>   		staticMetadata_->addEntry(ANDROID_SENSOR_INFO_EXPOSURE_TIME_RANGE,
>   					  exposureTimeRange, 2);
>   	}
>