[libcamera-devel] [PATCH v2 2/4] pipeline: vimc: Allocate fake IPA buffers

[Laurent Pinchart]

Hi Umang,

Thank you for the patch.

On Fri, Aug 13, 2021 at 08:14:35PM +0530, Umang Jain wrote:
> VIMC is a virtual test driver that doesn't generate statistics or
> consume parameters buffers. Thus, create simple (single plane)
> dmabuf-backed FrameBuffers, which can act as fake IPA buffers and
> can be memory mapped(mmap) to VIMC IPA.
> 
> To create these buffers, temporarily hijack the output video node
> and configure it with a V4L2DeviceFormat. Buffers then can be exported
> from the output video node using V4L2VideoDevice::exportBuffers().
> These buffers will be mimicked as IPA buffers in subsequent commits.
> 
> Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
> ---
>  src/libcamera/pipeline/vimc/vimc.cpp | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/src/libcamera/pipeline/vimc/vimc.cpp b/src/libcamera/pipeline/vimc/vimc.cpp
> index 4c92729d..edf8c58e 100644
> --- a/src/libcamera/pipeline/vimc/vimc.cpp
> +++ b/src/libcamera/pipeline/vimc/vimc.cpp
> @@ -50,6 +50,7 @@ public:
>  	}
>  
>  	int init();
> +	int allocateMockIPABuffers();
>  	void bufferReady(FrameBuffer *buffer);
>  
>  	MediaDevice *media_;
> @@ -61,6 +62,7 @@ public:
>  	Stream stream_;
>  
>  	std::unique_ptr<ipa::vimc::IPAProxyVimc> ipa_;
> +	std::vector<std::unique_ptr<FrameBuffer>> mockIPABufs_;
>  };
>  
>  class VimcCameraConfiguration : public CameraConfiguration
> @@ -500,6 +502,12 @@ int VimcCameraData::init()
>  	if (raw_->open())
>  		return -ENODEV;
>  
> +	ret = allocateMockIPABuffers();
> +	if (!ret) {
> +		LOG(VIMC, Warning) << "Cannot allocate fake IPA buffers";

I'd replace "fake" with "mock", as they're real buffers :-) Even "mock"
may not be totally accurate, we could talk about "mock statistics
buffers" instead of "mock buffers", but that's bikeshedding.

> +		/* \todo fail hard or continue? */

I don't see a reason why this should fail, so I'd make it a hard error.

> +	}
> +
>  	/* Initialise the supported controls. */
>  	const ControlInfoMap &controls = sensor_->controls();
>  	ControlInfoMap::Map ctrls;
> @@ -548,6 +556,25 @@ void VimcCameraData::bufferReady(FrameBuffer *buffer)
>  	pipe_->completeRequest(request);
>  }
>  
> +int VimcCameraData::allocateMockIPABuffers()
> +{
> +	unsigned int bufCount = 2;

	constexpr unsigned int kBufCount = 2;

> +
> +	V4L2DeviceFormat format;
> +	format.fourcc = video_->toV4L2PixelFormat(formats::BGR888);
> +	format.size = Size(160, 120);
> +
> +	int ret = video_->tryFormat(&format);
> +	if (ret < 0)
> +		return ret;

No need to call tryFormat(), setFormat() is enough.

With these small issues fixed,

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

> +
> +	ret = video_->setFormat(&format);
> +	if (ret < 0)
> +		return ret;
> +
> +	return video_->exportBuffers(bufCount, &mockIPABufs_);
> +}
> +
>  REGISTER_PIPELINE_HANDLER(PipelineHandlerVimc)
>  
>  } /* namespace libcamera */

-- 
Regards,

Laurent Pinchart