[libcamera-devel] [PATCH v2 3/3] pipeline: raspberrypi: Increase the V4L2BufferCache slot allocations

[Laurent Pinchart]

Hi Naush,

Thank you for the patch.

On Fri, Nov 12, 2021 at 10:03:05AM +0000, Naushir Patuck wrote:
> If a stream is marked as external, double the number of V4L2BufferCache slots
> that are allocated. This is to account for additional buffers that may be
> allocated directly by the application.
> 
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> Reviewed-by: Umang Jain <umang.jain at ideasonboard.com>
> ---
>  src/libcamera/pipeline/raspberrypi/rpi_stream.cpp | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/src/libcamera/pipeline/raspberrypi/rpi_stream.cpp b/src/libcamera/pipeline/raspberrypi/rpi_stream.cpp
> index b3265d0e8aab..67901936d6b6 100644
> --- a/src/libcamera/pipeline/raspberrypi/rpi_stream.cpp
> +++ b/src/libcamera/pipeline/raspberrypi/rpi_stream.cpp
> @@ -107,6 +107,14 @@ int Stream::prepareBuffers(unsigned int count)
>  		count = bufferMap_.size();
>  	}
>  
> +	/*
> +	 * If this is an external stream, we must allocate slots for buffers that
> +	 * might be externally allocated. We have no indication of how many buffers
> +	 * may be used, so this might overallocate slots in the buffer cache.

With

	 * \todo Find a better heuristic, or, even better, an exact solution to
	 * this issue

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

> +	 */
> +	if (isExternal())
> +		count = count * 2;
> +
>  	return dev_->importBuffers(count);
>  }
>  

-- 
Regards,

Laurent Pinchart