[libcamera-devel] [PATCH v2 3/4] libcamera: camera: add state machine to control access from applications

[Niklas Söderlund]

On 2019-02-28 03:16:25 +0100, Niklas Söderlund wrote:

[snip]

> diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
> index 84b97b5c2ce94ecf..4f0833300b9b7ffc 100644
> --- a/src/libcamera/camera.cpp
> +++ b/src/libcamera/camera.cpp

[snip]

> @@ -396,27 +549,22 @@ int Camera::start()
>   * requests are cancelled and complete synchronously in an error state.
>   *
>   * \return 0 on success or a negative error code otherwise
> + * \retval -ENODEV The camera is no longer connected to the hardware
> + * \retval -EACCES The camera is not running so can't be stopped
>   */
>  int Camera::stop()
>  {
> -	int ret = exclusiveAccess();
> -	if (ret)
> -		return ret;
> +	if (disconnected_)
> +		return -ENODEV;
> +
> +	if (!stateIs(CameraRunning))
> +		return -EACCES;
>  
>  	LOG(Camera, Debug) << "Stopping capture";
>  
>  	pipe_->stop(this);
>  
> -	return 0;
> -}
> -
> -int Camera::exclusiveAccess()
> -{
> -	if (disconnected_)
> -		return -ENODEV;
> -
> -	if (!acquired_)
> -		return -EACCES;
> +	state_ = CameraPrepared;

After a discussion on IRC it is agreed that the order of these 
operations should be swapped for next version,

    state_ = CameraPrepared;
    pipe_->stop(this)

Instead of how this patch changes it,

    pipe_->stop(this)
    state_ = CameraPrepared;

>  
>  	return 0;
>  }

-- 
Regards,
Niklas Söderlund