[libcamera-devel] [PATCH v1 3/3] pipeline: raspberrypi: Add a Unicam dequeue timeout

[Laurent Pinchart]

Hi Naush,

Thank you for the patch.

On Tue, Mar 22, 2022 at 01:16:35PM +0000, Naushir Patuck via libcamera-devel wrote:
> Enable the V4L2VideoDevice dequeue timeout for the Unicam Image node, and
> connect the timeout signal to a slot in the pipeline handler. This slot will
> log a fatal error message informing the user of a possible hardware stall.
> 
> The timeout is calculated as 2x the maximum frame length possible for a given
> mode, returned by the IPA.
> 
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> ---
>  include/libcamera/ipa/raspberrypi.mojom           |  1 +
>  src/ipa/raspberrypi/raspberrypi.cpp               |  2 ++
>  .../pipeline/raspberrypi/raspberrypi.cpp          | 15 +++++++++++++++
>  3 files changed, 18 insertions(+)
> 
> diff --git a/include/libcamera/ipa/raspberrypi.mojom b/include/libcamera/ipa/raspberrypi.mojom
> index acd3cafe6c91..5a228b75cd2f 100644
> --- a/include/libcamera/ipa/raspberrypi.mojom
> +++ b/include/libcamera/ipa/raspberrypi.mojom
> @@ -41,6 +41,7 @@ struct IPAConfig {
>  struct StartConfig {
>  	libcamera.ControlList controls;
>  	int32 dropFrameCount;
> +	uint32 maxSensorFrameLengthMs;

We really need duration types in mojo.

>  };
>  
>  interface IPARPiInterface {
> diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp
> index fd8fecb07f81..675f9ba1b350 100644
> --- a/src/ipa/raspberrypi/raspberrypi.cpp
> +++ b/src/ipa/raspberrypi/raspberrypi.cpp
> @@ -280,6 +280,8 @@ void IPARPi::start(const ControlList &controls, ipa::RPi::StartConfig *startConf
>  	}
>  
>  	startConfig->dropFrameCount = dropFrameCount_;
> +	const Duration maxSensorFrameDuration = mode_.max_frame_length * mode_.line_length;
> +	startConfig->maxSensorFrameLengthMs = maxSensorFrameDuration.get<std::milli>();
>  
>  	firstStart_ = false;
>  	lastRunTimestamp_ = 0;
> diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> index c2230199fed7..50b39f1adf93 100644
> --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> @@ -45,6 +45,8 @@
>  #include "dma_heaps.h"
>  #include "rpi_stream.h"
>  
> +using namespace std::literals::chrono_literals;
> +
>  namespace libcamera {
>  
>  LOG_DEFINE_CATEGORY(RPI)
> @@ -202,6 +204,7 @@ public:
>  	void setIspControls(const ControlList &controls);
>  	void setDelayedControls(const ControlList &controls);
>  	void setSensorControls(ControlList &controls);
> +	void unicamTimeout(V4L2VideoDevice *dev);
>  
>  	/* bufferComplete signal handlers. */
>  	void unicamBufferDequeue(FrameBuffer *buffer);
> @@ -1032,6 +1035,12 @@ int PipelineHandlerRPi::start(Camera *camera, const ControlList *controls)
>  		}
>  	}
>  
> +	/* Set the dequeue timeout to 2x the maximum possible frame duration. */
> +	utils::Duration duration = startConfig.maxSensorFrameLengthMs * 2 * 1ms;
> +	data->unicam_[Unicam::Image].dev()->setDequeueTimeout(duration);
> +	data->unicam_[Unicam::Image].dev()->dequeueTimeout.connect(data, &RPiCameraData::unicamTimeout);
> +	LOG(RPI, Debug) << "Setting sensor timeout to " << duration;
> +
>  	return 0;
>  }
>  
> @@ -1040,6 +1049,7 @@ void PipelineHandlerRPi::stopDevice(Camera *camera)
>  	RPiCameraData *data = cameraData(camera);
>  
>  	data->state_ = RPiCameraData::State::Stopped;
> +	data->unicam_[Unicam::Image].dev()->dequeueTimeout.disconnect();

No need to connect and disconnect the signal when starting and stopping,
you can connect it at init time and keep it connected forever.

>  
>  	/* Disable SOF event generation. */
>  	data->unicam_[Unicam::Image].dev()->setFrameStartEnabled(false);
> @@ -1757,6 +1767,11 @@ void RPiCameraData::setSensorControls(ControlList &controls)
>  	sensor_->setControls(&controls);
>  }
>  
> +void RPiCameraData::unicamTimeout([[maybe_unused]] V4L2VideoDevice *dev)
> +{
> +	LOG(RPI, Fatal) << "Unicam has timed out!";

That's harsh, and is likely to trigger if we ever miss a frame due to
high CPU load. If the goal is to detect a complete stall, I'd increase
the timeout to at least 10 frames.

How will this work with sensors that use an external trigger ?

> +}
> +
>  void RPiCameraData::unicamBufferDequeue(FrameBuffer *buffer)
>  {
>  	RPi::Stream *stream = nullptr;

-- 
Regards,

Laurent Pinchart