[libcamera-devel] [PATCH 1/3] libcamera: controls: Destage 'SensorTimestamp'

[Niklas Söderlund]

Hi Jacopo,

Thanks for your work.

On 2021-04-07 18:06:42 +0200, Jacopo Mondi wrote:
> Destage the 'SensorTimestamp' control, which is used by pipeline
> handlers to report the time when the first active line of the sensor's
> pixel array is exposed.
> 
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> ---
>  src/libcamera/control_ids.yaml | 21 ++++++++++++++-------
>  1 file changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/src/libcamera/control_ids.yaml b/src/libcamera/control_ids.yaml
> index b4771f9def89..f025819aedfd 100644
> --- a/src/libcamera/control_ids.yaml
> +++ b/src/libcamera/control_ids.yaml
> @@ -360,6 +360,20 @@ controls:
>  
>        size: [2]
>  
> +  - SensorTimestamp:
> +      type: int64_t
> +      description: |
> +        The time when the first row of the image sensor active array is exposed,
> +        The timestamp represents a monotonically increasing counter since the
> +        system boot time expressed in nanoseconds.

Is it wise to state that time time counter is increasing since system 
boot?  To me that reads as the counter would start at 0 at system boot 
and that I could calculate uptime from it. Even if this is true on some 
platforms I'm sure there are others where it's not. How about,

    A timestamp when the first row of the image sensor active array is 
    exposed. The timestamp represents a monotonically increasing counter 
    expressed in nanoseconds.

> +
> +        Pipeline handlers set this control in a completed Request metadata to
> +        allow application to compute the sensor's frame period duration by
> +        comparing consecutive capture results.
> +
> +        \todo Define how the sensor timestamp has to be used in the reprocessing
> +        use case.
> +
>    # ----------------------------------------------------------------------------
>    # Draft controls section
>  
> @@ -547,13 +561,6 @@ controls:
>            value: 3
>            description: The AWB algorithm is locked.
>  
> -  - SensorTimestamp:
> -      type: int64_t
> -      draft: true
> -      description: |
> -       Control to report the start of exposure of the first row of the captured
> -       image. Currently identical to ANDROID_SENSOR_TIMESTAMP.
> -
>    - SensorRollingShutterSkew:
>        type: int64_t
>        draft: true
> -- 
> 2.31.1
> 
> _______________________________________________
> libcamera-devel mailing list
> libcamera-devel at lists.libcamera.org
> https://lists.libcamera.org/listinfo/libcamera-devel

-- 
Regards,
Niklas Söderlund