[PATCH v7 2/7] libcamera: Remove PipelineHandler Fatal check of non-empty MediaDevices

[Laurent Pinchart]

Hi Chenghao,

Thank you for the patch.

On Thu, Aug 01, 2024 at 07:30:58AM +0000, Harvey Yang wrote:
> The Fatal check of having at least one MediaDevice was to prevent
> pipeline handler implementations searching and owning media devices with
> custom conventions, instead of using the base function
> |acquireMediaDevice|. It also has the assumption that there's at least
> one media device to make a camera work.
> 
> Now that the assumption will be broken by the virtual pipeline handler
> added in the following patches, and developers should be aware of the
> available functions in the base class to handle media devices, the Fatal
> check is no longer needed.
> 
> Signed-off-by: Harvey Yang <chenghaoyang at chromium.org>

That's a bit of a hack. It would be nicer to rework the device matching
logic to support other types of devices than media devices. That would
be quite a lot of yak shaving though, I suppose we can live with this
patch for now.

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

> ---
>  src/libcamera/pipeline_handler.cpp | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> index 5ea2ca78..125cf9d5 100644
> --- a/src/libcamera/pipeline_handler.cpp
> +++ b/src/libcamera/pipeline_handler.cpp
> @@ -605,9 +605,14 @@ void PipelineHandler::registerCamera(std::shared_ptr<Camera> camera)
>  {
>  	cameras_.push_back(camera);
>  
> -	if (mediaDevices_.empty())
> -		LOG(Pipeline, Fatal)
> -			<< "Registering camera with no media devices!";
> +	if (mediaDevices_.empty()) {
> +		/*
> +		 * For virtual devices with no MediaDevice, there are no system
> +		 * devices to register.
> +		 */
> +		manager_->_d()->addCamera(std::move(camera));
> +		return;
> +	}
>  
>  	/*
>  	 * Walk the entity list and map the devnums of all capture video nodes

-- 
Regards,

Laurent Pinchart