[PATCH v2 1/4] converter: converter_v4l2_m2m: Rectify streams sanity check

[Kieran Bingham]

Quoting Umang Jain (2024-05-29 08:02:45)
> The streams sanity check tries to determine if all the stream indexes
> passed in outputs std::map<> are unique. However, since the data
> container is std::map<>, all its keys (stream indexes in this case),
> are already unique.

Good point ;-) So the current mask is fairly redundant...

> 
> Instead, rectify the sanity check to ensure all the framebuffers passed
> in the outputs std::map<> are unique to each index. Hence, no two stream
> indexes should have same framebuffer. Update the comment to reflect
> the change.

I was going to say surely this is just a precursor to the next patches,
but I do think it holds up on it's own now I realised the index is
indeed already a std::map key...


Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

> Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
> ---
>  src/libcamera/converter/converter_v4l2_m2m.cpp | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/src/libcamera/converter/converter_v4l2_m2m.cpp b/src/libcamera/converter/converter_v4l2_m2m.cpp
> index d8929fc5..27a50e34 100644
> --- a/src/libcamera/converter/converter_v4l2_m2m.cpp
> +++ b/src/libcamera/converter/converter_v4l2_m2m.cpp
> @@ -403,13 +403,13 @@ void V4L2M2MConverter::stop()
>  int V4L2M2MConverter::queueBuffers(FrameBuffer *input,
>                                    const std::map<unsigned int, FrameBuffer *> &outputs)
>  {
> -       unsigned int mask = 0;
> +       std::set<FrameBuffer *> outputBufs;
>         int ret;
>  
>         /*
>          * Validate the outputs as a sanity check: at least one output is
>          * required, all outputs must reference a valid stream and no two
> -        * outputs can reference the same stream.
> +        * streams can reference same output framebuffers.
>          */
>         if (outputs.empty())
>                 return -EINVAL;
> @@ -419,12 +419,13 @@ int V4L2M2MConverter::queueBuffers(FrameBuffer *input,
>                         return -EINVAL;
>                 if (index >= streams_.size())
>                         return -EINVAL;
> -               if (mask & (1 << index))
> -                       return -EINVAL;
>  
> -               mask |= 1 << index;
> +               outputBufs.insert(buffer);
>         }
>  
> +       if (outputBufs.size() != streams_.size())
> +               return -EINVAL;
> +
>         /* Queue the input and output buffers to all the streams. */
>         for (auto [index, buffer] : outputs) {
>                 ret = streams_[index].queueBuffers(input, buffer);
> -- 
> 2.44.0
>