[libcamera-devel] [PATCH v2 01/10] libcamera: request: Add support for error flags

[Umang Jain]

Hi Jacopo,

Thank you for the patch.

On 8/5/22 19:23, Jacopo Mondi via libcamera-devel wrote:
> From: Paul Elder <paul.elder at ideasonboard.com>
>
> Add error flags to the Request to indicate non-fatal errors.
>
> Applications should check the error() state of the Request to determine
> if any fault occurred while processing the request.
>
> Initially, a single error flag ControlError is added to allow a pipeline
> handler to report a failure to set controls on a hardware device while
> processing the request.
>
> ControlError occurs when a Request was asked to set a control and the
> pipeline handler attempted to do so, but it was rejected by the kernel.
>
> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>


Reviewed-by: Umang Jain <umang.jain at ideasonboard.com>

> ---
>   include/libcamera/internal/request.h |  4 ++
>   include/libcamera/request.h          |  9 ++++
>   src/libcamera/request.cpp            | 72 ++++++++++++++++++++++++++--
>   3 files changed, 81 insertions(+), 4 deletions(-)
>
> diff --git a/include/libcamera/internal/request.h b/include/libcamera/internal/request.h
> index 9dadd6c60361..76cc32f73f9c 100644
> --- a/include/libcamera/internal/request.h
> +++ b/include/libcamera/internal/request.h
> @@ -42,6 +42,8 @@ public:
>   	void prepare(std::chrono::milliseconds timeout = 0ms);
>   	Signal<> prepared;
>   
> +	void setError(Errors error);
> +
>   private:
>   	friend class PipelineHandler;
>   	friend std::ostream &operator<<(std::ostream &out, const Request &r);
> @@ -59,6 +61,8 @@ private:
>   	std::unordered_set<FrameBuffer *> pending_;
>   	std::map<FrameBuffer *, std::unique_ptr<EventNotifier>> notifiers_;
>   	std::unique_ptr<Timer> timer_;
> +
> +	Errors errors_;
>   };
>   
>   } /* namespace libcamera */
> diff --git a/include/libcamera/request.h b/include/libcamera/request.h
> index dffde1536cad..3304da31200d 100644
> --- a/include/libcamera/request.h
> +++ b/include/libcamera/request.h
> @@ -15,6 +15,7 @@
>   #include <unordered_set>
>   
>   #include <libcamera/base/class.h>
> +#include <libcamera/base/flags.h>
>   #include <libcamera/base/signal.h>
>   
>   #include <libcamera/controls.h>
> @@ -43,6 +44,13 @@ public:
>   		ReuseBuffers = (1 << 0),
>   	};
>   
> +	enum ErrorFlag {
> +		NoError = 0,
> +		ControlError = (1 << 0),
> +	};
> +
> +	using Errors = Flags<ErrorFlag>;
> +
>   	using BufferMap = std::map<const Stream *, FrameBuffer *>;
>   
>   	Request(Camera *camera, uint64_t cookie = 0);
> @@ -60,6 +68,7 @@ public:
>   	uint32_t sequence() const;
>   	uint64_t cookie() const { return cookie_; }
>   	Status status() const { return status_; }
> +	Errors error() const;
>   
>   	bool hasPendingBuffers() const;
>   
> diff --git a/src/libcamera/request.cpp b/src/libcamera/request.cpp
> index d2af1d2212ad..9a808f19fc03 100644
> --- a/src/libcamera/request.cpp
> +++ b/src/libcamera/request.cpp
> @@ -162,6 +162,7 @@ void Request::Private::cancel()
>    */
>   void Request::Private::reuse()
>   {
> +	errors_ = Request::NoError;
>   	sequence_ = 0;
>   	cancelled_ = false;
>   	prepared_ = false;
> @@ -284,6 +285,21 @@ void Request::Private::notifierActivated(FrameBuffer *buffer)
>   	emitPrepareCompleted();
>   }
>   
> +/**
> + * \brief Update the error flags of the Request
> + * \param[in] error Error flags to apply on the Request
> + *
> + * Flag \a error in the Request which will get reported to the application when
> + * the Request completes.
> + *
> + * Setting an error flag does not cause a Request to fail, and once set it can
> + * only be cleared by the application destroying the Request or calling reuse().
> + */
> +void Request::Private::setError(Errors error)
> +{
> +	errors_ |= error;
> +}
> +
>   void Request::Private::timeout()
>   {
>   	/* A timeout can only happen if there are fences not yet signalled. */
> @@ -318,6 +334,25 @@ void Request::Private::timeout()
>    * Reuse the buffers that were previously added by addBuffer()
>    */
>   
> +/**
> + * \enum Request::ErrorFlag
> + * Flags to report errors on a completed request
> + *
> + * \var Request::NoError
> + * No error. The Request completed succesfully and all its buffer contain
> + * valid data
> + *
> + * \var Request::ControlError
> + * Control Error. At least one control was not applied correctly to the camera.
> + * The application should compare the metadata to the requested control values
> + * to check which controls weren't applied.
> + */
> +
> +/**
> + * \typedef Request::Errors
> + * The error state of the request defined by \a Request::ErrorFlag
> + */
> +
>   /**
>    * \typedef Request::BufferMap
>    * \brief A map of Stream to FrameBuffer pointers
> @@ -552,14 +587,43 @@ uint32_t Request::sequence() const
>    * \brief Retrieve the request completion status
>    *
>    * The request status indicates whether the request has completed successfully
> - * or with an error. When requests are created and before they complete the
> - * request status is set to RequestPending, and is updated at completion time
> - * to RequestComplete. If a request is cancelled at capture stop before it has
> - * completed, its status is set to RequestCancelled.
> + * or has been cancelled before being processed.
> + *
> + * Requests are created with their status set to RequestPending. When
> + * a Request is successfully processed and completed by the Camera its
> + * status is set to RequestComplete. If a Request is cancelled before
> + * being processed, for example because the Camera has been stopped
> + * before the request is completed, its status is set to RequestCancelled.
> + *
> + * Successfully completed requests can complete with errors. Applications shall
> + * inspect the error mask returned by Request::error() before accessing buffers
> + * and data associated with a completed request.
>    *
>    * \return The request completion status
>    */
>   
> +/**
> + * \brief Retrieve the mask of error flags associated with a completed request
> + *
> + * The request could complete with errors, which indicate failures in
> + * completing correctly parts of the request submitted by the application.
> + *
> + * The possible failure reasons are defined by the error flags defined
> + * by Request::ErrorFlag and application are expected to retrieve the
> + * mask of error flags by using this function before accessing the
> + * buffers and data associated with a completed request.
> + *
> + * Error conditions reported through this function do not change the
> + * request completion status retrieved through Request::status() which
> + * indicates if the Request has been processed or not.
> + *
> + * \return A mask of error identifier with which the request was completed
> + */
> +Request::Errors Request::error() const
> +{
> +	return _d()->errors_;
> +}
> +
>   /**
>    * \brief Check if a request has buffers yet to be completed
>    *