[RFC PATCH 1/3] drm/vkms: decouple cursor plane setup from crtc_init

[Daniel Vetter]

On Sat, Feb 20, 2021 at 11:38:50AM -0300, Melissa Wen wrote:
> Initialize CRTC only with primary plane (without cursor) as a preparation
> to init overlay plane before cursor plane and keep cursor on the top.
> 
> Signed-off-by: Melissa Wen <melissa.srw at gmail.com>

Why can't we first initialize all the planes (primary, cursor, overlay)
and then the crtc?

For drivers where there's not really a functional difference between these
planes (like vkms, since it's all sw, only difference is z position
really) the usual approach is to initialize all planes in a loop. And then
call crtc init with the first and last plane for that crtc.

Passing NULL for the cursor for crtc_init and then patching it up
afterwards is a bit a hack, so would be good to avoid that.
-Daniel

> ---
>  drivers/gpu/drm/vkms/vkms_crtc.c   |  4 ++--
>  drivers/gpu/drm/vkms/vkms_drv.h    |  2 +-
>  drivers/gpu/drm/vkms/vkms_output.c | 14 +++++++++-----
>  3 files changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
> index 0443b7deeaef..2d4cd7736933 100644
> --- a/drivers/gpu/drm/vkms/vkms_crtc.c
> +++ b/drivers/gpu/drm/vkms/vkms_crtc.c
> @@ -270,12 +270,12 @@ static const struct drm_crtc_helper_funcs vkms_crtc_helper_funcs = {
>  };
>  
>  int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
> -		   struct drm_plane *primary, struct drm_plane *cursor)
> +		   struct drm_plane *primary)
>  {
>  	struct vkms_output *vkms_out = drm_crtc_to_vkms_output(crtc);
>  	int ret;
>  
> -	ret = drm_crtc_init_with_planes(dev, crtc, primary, cursor,
> +	ret = drm_crtc_init_with_planes(dev, crtc, primary, NULL,
>  					&vkms_crtc_funcs, NULL);
>  	if (ret) {
>  		DRM_ERROR("Failed to init CRTC\n");
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> index 35540c7c4416..9ad5ad8b7737 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.h
> +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> @@ -110,7 +110,7 @@ struct vkms_device {
>  
>  /* CRTC */
>  int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
> -		   struct drm_plane *primary, struct drm_plane *cursor);
> +		   struct drm_plane *primary);
>  
>  int vkms_output_init(struct vkms_device *vkmsdev, int index);
>  
> diff --git a/drivers/gpu/drm/vkms/vkms_output.c b/drivers/gpu/drm/vkms/vkms_output.c
> index f5f6f15c362c..05d3bb45e6c1 100644
> --- a/drivers/gpu/drm/vkms/vkms_output.c
> +++ b/drivers/gpu/drm/vkms/vkms_output.c
> @@ -47,6 +47,10 @@ int vkms_output_init(struct vkms_device *vkmsdev, int index)
>  	if (IS_ERR(primary))
>  		return PTR_ERR(primary);
>  
> +	ret = vkms_crtc_init(dev, crtc, primary);
> +	if (ret)
> +		goto err_crtc;
> +
>  	if (vkmsdev->config->cursor) {
>  		cursor = vkms_plane_init(vkmsdev, DRM_PLANE_TYPE_CURSOR, index);
>  		if (IS_ERR(cursor)) {
> @@ -55,9 +59,9 @@ int vkms_output_init(struct vkms_device *vkmsdev, int index)
>  		}
>  	}
>  
> -	ret = vkms_crtc_init(dev, crtc, primary, cursor);
> -	if (ret)
> -		goto err_crtc;
> +	crtc->cursor = cursor;
> +	if (cursor && !cursor->possible_crtcs)
> +		cursor->possible_crtcs = drm_crtc_mask(crtc);
>  
>  	ret = drm_connector_init(dev, connector, &vkms_connector_funcs,
>  				 DRM_MODE_CONNECTOR_VIRTUAL);
> @@ -100,11 +104,11 @@ int vkms_output_init(struct vkms_device *vkmsdev, int index)
>  err_connector:
>  	drm_crtc_cleanup(crtc);
>  
> -err_crtc:
> +err_cursor:
>  	if (vkmsdev->config->cursor)
>  		drm_plane_cleanup(cursor);
>  
> -err_cursor:
> +err_crtc:
>  	drm_plane_cleanup(primary);
>  
>  	return ret;
> -- 
> 2.30.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch