[libcamera-devel] [PATCH v3 7/8] cam: kms_sink: Enable display on first frame

[Umang Jain]

On 8/4/21 6:13 PM, Laurent Pinchart wrote:
> Not all display controllers support enabling the display without any
> active plane. Delay display enabling to the first frame.
>
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Reviewed-by: Paul Elder <paul.elder at ideasonboard.com>
> ---
>   src/cam/kms_sink.cpp | 31 +++++++++++--------------------
>   src/cam/kms_sink.h   |  2 --
>   2 files changed, 11 insertions(+), 22 deletions(-)
>
> diff --git a/src/cam/kms_sink.cpp b/src/cam/kms_sink.cpp
> index f708b613f226..d9a2efe84c59 100644
> --- a/src/cam/kms_sink.cpp
> +++ b/src/cam/kms_sink.cpp
> @@ -193,23 +193,6 @@ int KMSSink::start()
>   		return ret;
>   	}
>   
> -	/* Enable the display pipeline with no plane to start with. */
> -	request = std::make_unique<DRM::AtomicRequest>(&dev_);
> -
> -	request->addProperty(connector_, "CRTC_ID", crtc_->id());
> -	request->addProperty(crtc_, "ACTIVE", 1);
> -	request->addProperty(crtc_, "MODE_ID", mode_->toBlob(&dev_));
> -
> -	ret = request->commit(DRM::AtomicRequest::FlagAllowModeset);
> -	if (ret < 0) {
> -		std::cerr
> -			<< "Failed to enable display pipeline: "
> -			<< strerror(-ret) << std::endl;
> -		return ret;
> -	}
> -
> -	planeInitialized_ = false;
> -
>   	return 0;
>   }
>   
> @@ -253,10 +236,17 @@ bool KMSSink::processRequest(libcamera::Request *camRequest)
>   
>   	DRM::FrameBuffer *drmBuffer = iter->second.get();
>   
> +	unsigned int flags = DRM::AtomicRequest::FlagAsync;
>   	DRM::AtomicRequest *drmRequest = new DRM::AtomicRequest(&dev_);
>   	drmRequest->addProperty(plane_, "FB_ID", drmBuffer->id());
>   
> -	if (!planeInitialized_) {
> +	if (!active_ && !queued_) {

Ah, this was misleading at first as I was reasoning, if we don't have 
any active_ or queued_, how could we init? Isn't this the same thing as 
before (init without any plane).

But then noticed, we have set the "FB_ID" just before, so it shall 
applied while commit() below, and hence we have init the display 
controller for first frame.

Reviewed-by: Umang Jain <umang.jain at ideasonboard.com>

> +		/* Enable the display pipeline on the first frame. */
> +		drmRequest->addProperty(connector_, "CRTC_ID", crtc_->id());
> +
> +		drmRequest->addProperty(crtc_, "ACTIVE", 1);
> +		drmRequest->addProperty(crtc_, "MODE_ID", mode_->toBlob(&dev_));
> +
>   		drmRequest->addProperty(plane_, "CRTC_ID", crtc_->id());
>   		drmRequest->addProperty(plane_, "SRC_X", 0 << 16);
>   		drmRequest->addProperty(plane_, "SRC_Y", 0 << 16);
> @@ -266,7 +256,8 @@ bool KMSSink::processRequest(libcamera::Request *camRequest)
>   		drmRequest->addProperty(plane_, "CRTC_Y", 0);
>   		drmRequest->addProperty(plane_, "CRTC_W", mode_->hdisplay);
>   		drmRequest->addProperty(plane_, "CRTC_H", mode_->vdisplay);
> -		planeInitialized_ = true;
> +
> +		flags |= DRM::AtomicRequest::FlagAllowModeset;
>   	}
>   
>   	pending_ = std::make_unique<Request>(drmRequest, camRequest);
> @@ -274,7 +265,7 @@ bool KMSSink::processRequest(libcamera::Request *camRequest)
>   	std::lock_guard<std::mutex> lock(lock_);
>   
>   	if (!queued_) {
> -		int ret = drmRequest->commit(DRM::AtomicRequest::FlagAsync);
> +		int ret = drmRequest->commit(flags);
>   		if (ret < 0)
>   			std::cerr
>   				<< "Failed to commit atomic request: "
> diff --git a/src/cam/kms_sink.h b/src/cam/kms_sink.h
> index 2895e00f84a1..cd6f900d692c 100644
> --- a/src/cam/kms_sink.h
> +++ b/src/cam/kms_sink.h
> @@ -63,8 +63,6 @@ private:
>   	libcamera::Size size_;
>   	unsigned int stride_;
>   
> -	bool planeInitialized_;
> -
>   	std::map<libcamera::FrameBuffer *, std::unique_ptr<DRM::FrameBuffer>> buffers_;
>   
>   	std::mutex lock_;