Re: [PATCH/RFC v2 4/4] v4l: vsp1: Add HGO support

Hi Guennadi,

On Monday 13 Jun 2016 17:33:01 Guennadi Liakhovetski wrote:

On Thu, 12 May 2016, Laurent Pinchart wrote:

quoted

The HGO is a Histogram Generator One-Dimension. It computes per-channel
histograms over a configurable region of the image with optional
subsampling.

Signed-off-by: Laurent Pinchart
[off-list ref]

[snip]

Do I understand this correctly, that with this if such a metadata device
is opened, while no video data is streaming, all calls will succeed, but
no buffers will be dequeued, i.e. the user-space application will hang in
DQBUF or poll() / select() indefinitely?

That's correct. Same as with a mem-to-mem device, if you open the capture 
node, queue buffers and start streaming, DQBUF will wait until you start 
supplying buffers on the node at the other end of the pipeline.

-- 
Regards,

Laurent Pinchart