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

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Message-ID: <CAC=S1njFSULdpTefLpb8biEUARVH4c_dZndUav_S-6D-bstn6w@mail.gmail.com>
Date: Thu, 18 Jul 2024 17:50:37 +0800
From: Fei Shao <fshao@...omium.org>
To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
Cc: chunkuang.hu@...nel.org, p.zabel@...gutronix.de, airlied@...il.com, 
	daniel@...ll.ch, matthias.bgg@...il.com, shawn.sung@...iatek.com, 
	ck.hu@...iatek.com, dri-devel@...ts.freedesktop.org, 
	linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, kernel@...labora.com
Subject: Re: [PATCH] drm/mediatek: Declare Z Position for all planes

On Thu, Jul 18, 2024 at 4:25 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@...labora.com> 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.
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>

Reviewed-by: Fei Shao <fshao@...omium.org>
> ---
>  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
> --
> 2.45.2
>
>