[libcamera-devel] [PATCH] cam: Fail capture if to few Requests asked for

[Jacopo Mondi]

Hi Niklas,

On Mon, Feb 08, 2021 at 10:44:16AM +0100, Niklas Söderlund wrote:
> Running cam with the --capture=N option only queues N Requests to the
> camera. If N is less then the number of requests needed by the camera to
> operate cam may deadlock waiting for the camera to complete requests
> while the camera waits for the application to give it more buffers.
>
> Fix this by adding a check in cam to no attempt a capture session if to
> few requests are requested.
>
> Reported-by: Sebastian Fricke <sebastian.fricke at posteo.net>
> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> ---
>  src/cam/capture.cpp | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/src/cam/capture.cpp b/src/cam/capture.cpp
> index 7b55fc6770225e2a..18aa97c7cdb55dcc 100644
> --- a/src/cam/capture.cpp
> +++ b/src/cam/capture.cpp
> @@ -90,6 +90,13 @@ int Capture::capture(FrameBufferAllocator *allocator)
>  		nbuffers = std::min(nbuffers, allocated);
>  	}
>
> +	if (captureLimit_ && captureLimit_ < nbuffers) {
> +		std::cerr << "Camera requiers at least " << nbuffers

s/requiers/requires

> +			  << " reqests to function, " << captureLimit_

s/reqests/requests

> +			  << " requested" << std::endl;

I would make it shorter
                        << "Camera requires " << nbuffers << " requests, "
                        << "but only " << captureLimit_ << " have been provided";

Which is not that shorter :/

Up to you

Spelling fixes apart
Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>

Thanks
  j

> +		return -EINVAL;
> +	}
> +
>  	/*
>  	 * TODO: make cam tool smarter to support still capture by for
>  	 * example pushing a button. For now run all streams all the time.
> --
> 2.30.0
>
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