Re: [PATCH] drm/mediatek: Declare Z Position for all planes

["CK Hu (胡俊光)" <ck.hu@mediatek.com>]

Hi, Angelo:

On Thu, 2024-07-18 at 10:25 +0200, AngeloGioacchino Del Regno wrote:
> MediaTek SoCs support multiple planes, one of which is the primary
> and all the others are overlays (and CURSOR is the last overlay).
> 
> In all currently supported SoCs, the Z order of the overlays can't
> be changed with any fast muxing action, and can only be changed by
> swapping the contents of the entire register set of one overlay
> with the other to internally reorder the layer properties, which
> is indeed feasible, but probably more expensive than desired.
> 
> Declare the Z position for all planes with an immutable property
> at least for now, so that the userspace can take its decisions
> accordingly.

Reviewed-by: CK Hu <ck.hu@mediatek.com>

> 
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_crtc.c  |  2 +-
>  drivers/gpu/drm/mediatek/mtk_plane.c | 18 +++++++++++++++++-
>  drivers/gpu/drm/mediatek/mtk_plane.h |  3 +--
>  3 files changed, 19 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_crtc.c b/drivers/gpu/drm/mediatek/mtk_crtc.c
> index 072b2fdae87b..327214721b4d 100644
> --- a/drivers/gpu/drm/mediatek/mtk_crtc.c
> +++ b/drivers/gpu/drm/mediatek/mtk_crtc.c
> @@ -874,7 +874,7 @@ static int mtk_crtc_init_comp_planes(struct drm_device *drm_dev,
>  				mtk_crtc_plane_type(mtk_crtc->layer_nr, num_planes),
>  				mtk_ddp_comp_supported_rotations(comp),
>  				mtk_ddp_comp_get_formats(comp),
> -				mtk_ddp_comp_get_num_formats(comp));
> +				mtk_ddp_comp_get_num_formats(comp), i);
>  		if (ret)
>  			return ret;
>  
> diff --git a/drivers/gpu/drm/mediatek/mtk_plane.c b/drivers/gpu/drm/mediatek/mtk_plane.c
> index 5bf757a3ef20..7d2cb4e0fafa 100644
> --- a/drivers/gpu/drm/mediatek/mtk_plane.c
> +++ b/drivers/gpu/drm/mediatek/mtk_plane.c
> @@ -321,7 +321,7 @@ static const struct drm_plane_helper_funcs mtk_plane_helper_funcs = {
>  int mtk_plane_init(struct drm_device *dev, struct drm_plane *plane,
>  		   unsigned long possible_crtcs, enum drm_plane_type type,
>  		   unsigned int supported_rotations, const u32 *formats,
> -		   size_t num_formats)
> +		   size_t num_formats, unsigned int plane_idx)
>  {
>  	int err;
>  
> @@ -338,6 +338,22 @@ int mtk_plane_init(struct drm_device *dev, struct drm_plane *plane,
>  		return err;
>  	}
>  
> +	/*
> +	 * The hardware does not support repositioning planes by muxing: their
> +	 * Z-position is infact fixed and the only way to change the actual
> +	 * order is to swap the contents of the entire register set of one
> +	 * overlay with another, which may be more expensive than desired.
> +	 *
> +	 * With no repositioning, the caller of this function guarantees that
> +	 * the plane_idx is correct. This means that, for example, the PRIMARY
> +	 * plane fed to this function will always have plane_idx zero.
> +	 */
> +	err = drm_plane_create_zpos_immutable_property(plane, plane_idx);
> +	if (err) {
> +		DRM_ERROR("Failed to create zpos property for plane %u\n", plane_idx);
> +		return err;
> +	}
> +
>  	if (supported_rotations) {
>  		err = drm_plane_create_rotation_property(plane,
>  							 DRM_MODE_ROTATE_0,
> diff --git a/drivers/gpu/drm/mediatek/mtk_plane.h b/drivers/gpu/drm/mediatek/mtk_plane.h
> index 231bb7aac947..5b177eac67b7 100644
> --- a/drivers/gpu/drm/mediatek/mtk_plane.h
> +++ b/drivers/gpu/drm/mediatek/mtk_plane.h
> @@ -49,6 +49,5 @@ to_mtk_plane_state(struct drm_plane_state *state)
>  int mtk_plane_init(struct drm_device *dev, struct drm_plane *plane,
>  		   unsigned long possible_crtcs, enum drm_plane_type type,
>  		   unsigned int supported_rotations, const u32 *formats,
> -		   size_t num_formats);
> -
> +		   size_t num_formats, unsigned int plane_idx);
>  #endif