[libcamera-devel] [PATCH 2/2] libcamera: pipeline: simple: Set format on sink pad during propagation

[Jacopo Mondi]

Hi Laurent,

On Wed, Oct 21, 2020 at 03:24:18AM +0300, Laurent Pinchart wrote:
> When propagating formats through the media controller pipeline, the
> simple pipeline handler retrieves the format on sink pads and sets it on
> source pads. This assumes that subdevs will propagate formats
> internally, as required by the V4L2 subdev API. However, in some cases,
> propagation isn't properly handled by the subdev driver.
>

Working around a driver issue then.

> When can work around this issue by setting the format on source pads
> instead of getting it. This will have the effect of trying to propgate
> the same format through the pipeline, possibly overriding the default
> format propagated by subdev drivers. It will however not cause the
> pipeline configuration to be invalid, as subdevs are required to
> constraint the format set on their sources based on the configuration of
> the sources, and this requirement is better implemented in kernel driver

s/sources/sinks ? If you are referring to the usual "formats shall be
propagated from sinks to sources" inside a subdev. Or are you
referring to cross-link formats ?

> than the format propagation requirement.
>

I don't see any real drawback in doing this, so:

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

Thanks
  j

> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  src/libcamera/pipeline/simple/simple.cpp | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/libcamera/pipeline/simple/simple.cpp b/src/libcamera/pipeline/simple/simple.cpp
> index 4b6f708e8fee..45ecefc59851 100644
> --- a/src/libcamera/pipeline/simple/simple.cpp
> +++ b/src/libcamera/pipeline/simple/simple.cpp
> @@ -386,7 +386,7 @@ int SimpleCameraData::setupFormats(V4L2SubdeviceFormat *format,
>
>  		if (source->entity() != sensor_->entity()) {
>  			V4L2Subdevice *subdev = pipe->subdev(source->entity());
> -			ret = subdev->getFormat(source->index(), format, whence);
> +			ret = subdev->setFormat(source->index(), format, whence);
>  			if (ret < 0)
>  				return ret;
>  		}
> --
> Regards,
>
> Laurent Pinchart
>
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