[libcamera-devel] [PATCH v3] cam: kms_sink: Remove limitation that camera and display must match

[Eric Curtin]

Another friendly reminder this adds value. The existing use cases are
unchanged (when identical capture and display resolutions are
displayed it uses that), but in the cases before in which we would
have failed, we attempt to draw from 0,0.

It's happens to me quite frequently that displays and cameras don't
match pixel for pixel.

Is mise le meas/Regards,

Eric Curtin


On Tue, 29 Mar 2022 at 14:02, Eric Curtin <ecurtin at redhat.com> wrote:
>
> There is a limitation that requires input and output to be pixel
> for pixel identical in terms of height and width. Remove this
> limitation to enable more hardware that doesn't match. Just start
> drawing from top right 0, 0 corner.
>
> Signed-off-by: Eric Curtin <ecurtin at redhat.com>
> ---
> Changes in v2:
> - Tested and support drawing from negative pixel range
>   kernel parameter (video=960x540 at 60) was useful here
> Changes in v3:
> - Much simplified version of the patch where we just attempt to
>   draw from point 0, 0. Only in the case where we do not find a
>   matching mode. Can expand to do centralization, scaling, etc.
>   in further patches if needs be.
> ---
>  src/cam/kms_sink.cpp | 22 +++++++++++++---------
>  1 file changed, 13 insertions(+), 9 deletions(-)
>
> diff --git a/src/cam/kms_sink.cpp b/src/cam/kms_sink.cpp
> index da579846..5847c4e1 100644
> --- a/src/cam/kms_sink.cpp
> +++ b/src/cam/kms_sink.cpp
> @@ -119,17 +119,21 @@ int KMSSink::configure(const libcamera::CameraConfiguration &config)
>                                                       mode.vdisplay == cfg.size.height;
>                                        });
>         if (iter == modes.end()) {
> -               std::cerr
> -                       << "No mode matching " << cfg.size.toString()
> -                       << std::endl;
> -               return -EINVAL;
> +                if (modes.empty()) {
> +                       std::cerr << "No modes\n";
> +                       return -EINVAL;
> +                }
> +
> +                mode_ = &modes[0];
>         }
> +        else {
> +                mode_ = &*iter;
> +        }
>
>         int ret = configurePipeline(cfg.pixelFormat);
>         if (ret < 0)
>                 return ret;
>
> -       mode_ = &*iter;
>         size_ = cfg.size;
>         stride_ = cfg.stride;
>
> @@ -297,12 +301,12 @@ bool KMSSink::processRequest(libcamera::Request *camRequest)
>                 drmRequest->addProperty(plane_, "CRTC_ID", crtc_->id());
>                 drmRequest->addProperty(plane_, "SRC_X", 0 << 16);
>                 drmRequest->addProperty(plane_, "SRC_Y", 0 << 16);
> -               drmRequest->addProperty(plane_, "SRC_W", mode_->hdisplay << 16);
> -               drmRequest->addProperty(plane_, "SRC_H", mode_->vdisplay << 16);
> +               drmRequest->addProperty(plane_, "SRC_W", size_.width << 16);
> +               drmRequest->addProperty(plane_, "SRC_H", size_.height << 16);
>                 drmRequest->addProperty(plane_, "CRTC_X", 0);
>                 drmRequest->addProperty(plane_, "CRTC_Y", 0);
> -               drmRequest->addProperty(plane_, "CRTC_W", mode_->hdisplay);
> -               drmRequest->addProperty(plane_, "CRTC_H", mode_->vdisplay);
> +               drmRequest->addProperty(plane_, "CRTC_W", size_.width);
> +               drmRequest->addProperty(plane_, "CRTC_H", size_.height);
>
>                 flags |= DRM::AtomicRequest::FlagAllowModeset;
>         }
> --
> 2.35.1
>