[libcamera-devel] [PATCH v4 7/8] libcamera: pipeline: rkisp1: Use SOF event to warn about late parameters

[Laurent Pinchart]

Hi Niklas,

Thank you for the patch.

On Tue, Dec 15, 2020 at 01:48:10AM +0100, Niklas Söderlund wrote:
> In the Timeline approach the idea was to delay queuing buffers to the
> device until the IPA had a chance to prepare the parameters buffer. A
> check was still added to warn if the IPA queued buffers before the
> parameters buffer was filled in.
> 
> This check happened much sooner then needed as the parameter buffers
> does not have to be ready when the buffer is queued but just before it's
> consumed. As the pipeline now has true knowledge of each SOF we can move
> the check there and remove the delaying of queuing of buffers.
> 
> This change really speeds up the IPA reactions as the delays used in the
> Timeline where approximated while with this change they are driven by
> events reported by the device.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> ---
>  src/libcamera/pipeline/rkisp1/rkisp1.cpp | 78 ++++++++----------------
>  1 file changed, 24 insertions(+), 54 deletions(-)
> 
> diff --git a/src/libcamera/pipeline/rkisp1/rkisp1.cpp b/src/libcamera/pipeline/rkisp1/rkisp1.cpp
> index 513a60b04e5f2e21..3851d94e7b133356 100644
> --- a/src/libcamera/pipeline/rkisp1/rkisp1.cpp
> +++ b/src/libcamera/pipeline/rkisp1/rkisp1.cpp
> @@ -41,7 +41,6 @@ namespace libcamera {
>  LOG_DEFINE_CATEGORY(RkISP1)
>  
>  class PipelineHandlerRkISP1;
> -class RkISP1ActionQueueBuffers;
>  class RkISP1CameraData;
>  
>  enum RkISP1ActionType {
> @@ -202,7 +201,6 @@ private:
>  			PipelineHandler::cameraData(camera));
>  	}
>  
> -	friend RkISP1ActionQueueBuffers;
>  	friend RkISP1CameraData;
>  	friend RkISP1Frames;
>  
> @@ -213,6 +211,7 @@ private:
>  	void bufferReady(FrameBuffer *buffer);
>  	void paramReady(FrameBuffer *buffer);
>  	void statReady(FrameBuffer *buffer);
> +	void frameStart(uint32_t sequence);
>  
>  	int allocateBuffers(Camera *camera);
>  	int freeBuffers(Camera *camera);
> @@ -347,53 +346,6 @@ RkISP1FrameInfo *RkISP1Frames::find(Request *request)
>  	return nullptr;
>  }
>  
> -class RkISP1ActionQueueBuffers : public FrameAction
> -{
> -public:
> -	RkISP1ActionQueueBuffers(unsigned int frame, RkISP1CameraData *data,
> -				 PipelineHandlerRkISP1 *pipe)
> -		: FrameAction(frame, QueueBuffers), data_(data), pipe_(pipe)
> -	{
> -	}
> -
> -protected:
> -	void run() override
> -	{
> -		RkISP1FrameInfo *info = data_->frameInfo_.find(frame());
> -		if (!info)
> -			LOG(RkISP1, Fatal) << "Frame not known";
> -
> -		/*
> -		 * \todo: If parameters are not filled a better method to handle
> -		 * the situation than queuing a buffer with unknown content
> -		 * should be used.
> -		 *
> -		 * It seems excessive to keep an internal zeroed scratch
> -		 * parameters buffer around as this should not happen unless the
> -		 * devices is under too much load. Perhaps failing the request
> -		 * and returning it to the application with an error code is
> -		 * better than queue it to hardware?
> -		 */
> -		if (!info->paramFilled)
> -			LOG(RkISP1, Error)
> -				<< "Parameters not ready on time for frame "
> -				<< frame();
> -
> -		pipe_->param_->queueBuffer(info->paramBuffer);
> -		pipe_->stat_->queueBuffer(info->statBuffer);
> -
> -		if (info->mainPathBuffer)
> -			pipe_->mainPath_.queueBuffer(info->mainPathBuffer);
> -
> -		if (info->selfPathBuffer)
> -			pipe_->selfPath_.queueBuffer(info->selfPathBuffer);
> -	}
> -
> -private:
> -	RkISP1CameraData *data_;
> -	PipelineHandlerRkISP1 *pipe_;
> -};
> -
>  int RkISP1CameraData::loadIPA()
>  {
>  	ipa_ = IPAManager::createIPA(pipe_, 1, 1);
> @@ -950,9 +902,14 @@ int PipelineHandlerRkISP1::queueRequestDevice(Camera *camera, Request *request)
>  	op.controls = { request->controls() };
>  	data->ipa_->processEvent(op);
>  
> -	data->timeline_.scheduleAction(std::make_unique<RkISP1ActionQueueBuffers>(data->frame_,
> -										  data,
> -										  this));
> +	param_->queueBuffer(info->paramBuffer);

Unless there's something I don't understand correctly, you're queuing
the parameters buffer (along with all the other buffers) immediately
when the request is received, and then write the parameters to the
buffer at a later time. That violates the V4L2 API, as you're not
supposed to write to a queued buffer, and could even crash the kernel if
the parameters end up being written when the driver is processing the
buffer (that's an issue that will need to be fixed in the kernel, but
when that will be the case, writing parameters to the buffer after
queuing it will definitely be broken).

As the rkisp1 pipeline handler is not the main target of this patch
series I'm not opposed to merging this to move forward with the IPU3,
but could you please fix this on top ASAP ?

> +	stat_->queueBuffer(info->statBuffer);
> +
> +	if (info->mainPathBuffer)
> +		mainPath_.queueBuffer(info->mainPathBuffer);
> +
> +	if (info->selfPathBuffer)
> +		selfPath_.queueBuffer(info->selfPathBuffer);
>  
>  	data->frame_++;
>  
> @@ -1102,6 +1059,7 @@ bool PipelineHandlerRkISP1::match(DeviceEnumerator *enumerator)
>  	mainPath_.bufferReady().connect(this, &PipelineHandlerRkISP1::bufferReady);
>  	selfPath_.bufferReady().connect(this, &PipelineHandlerRkISP1::bufferReady);
>  	stat_->bufferReady.connect(this, &PipelineHandlerRkISP1::statReady);
> +	isp_->frameStart.connect(this, &PipelineHandlerRkISP1::frameStart);
>  	param_->bufferReady.connect(this, &PipelineHandlerRkISP1::paramReady);
>  
>  	/*
> @@ -1181,8 +1139,6 @@ void PipelineHandlerRkISP1::statReady(FrameBuffer *buffer)
>  	if (!info)
>  		return;
>  
> -	data->timeline_.bufferReady(buffer);
> -
>  	if (data->frame_ <= buffer->metadata().sequence)
>  		data->frame_ = buffer->metadata().sequence + 1;
>  
> @@ -1192,6 +1148,20 @@ void PipelineHandlerRkISP1::statReady(FrameBuffer *buffer)
>  	data->ipa_->processEvent(op);
>  }
>  
> +void PipelineHandlerRkISP1::frameStart(uint32_t sequence)
> +{
> +	if (!activeCamera_)
> +		return;
> +
> +	RkISP1CameraData *data = cameraData(activeCamera_);
> +
> +	RkISP1FrameInfo *info = data->frameInfo_.find(sequence);
> +	if (!info || !info->paramFilled)
> +		LOG(RkISP1, Info)
> +			<< "Parameters not ready on time for frame "
> +			<< sequence;
> +}
> +
>  REGISTER_PIPELINE_HANDLER(PipelineHandlerRkISP1)
>  
>  } /* namespace libcamera */

-- 
Regards,

Laurent Pinchart