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Subject: Re: [PATCH] drm/stm: ltdc: attach immutable zpos property to planes
To:     Raphael GALLAIS-POU - foss <raphael.gallais-pou@foss.st.com>,
        "Philippe CORNU - foss" <philippe.cornu@foss.st.com>,
        Benjamin Gaignard <benjamin.gaignard@linaro.org>
CC:     David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
        "Maxime Coquelin" <mcoquelin.stm32@gmail.com>,
        Alexandre TORGUE - foss <alexandre.torgue@foss.st.com>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        "linux-stm32@st-md-mailman.stormreply.com" 
        <linux-stm32@st-md-mailman.stormreply.com>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Raphael GALLAIS-POU <raphael.gallais-pou@st.com>
References: <20210902152605.12420-1-raphael.gallais-pou@foss.st.com>
From:   yannick Fertre <yannick.fertre@foss.st.com>
Message-ID: <ab16c454-df90-d9b1-4be1-9460baaef876@foss.st.com>
Date:   Tue, 7 Sep 2021 08:55:32 +0200
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Hi Raphael,
thanks for the patch.

Acked-by: Yannick Fertre <yannick.fertre@foss.st.com>
Reviewed-by: Yannick Fertre <yannick.fertre@foss.st.com>

On 9/2/21 5:30 PM, Raphael GALLAIS-POU - foss wrote:
> Defines plane ordering by hard-coding an immutable Z position from the
> first plane, used as primary layer, to the next ones as overlay in order
> of instantiation.
> 
> This zpos is only an information as it is not possible to modify it,
> blending operations are still applied from the top to the bottom layer.
> 
> This patch helps to remove a warning message from the Android
> Hardware Composer.
> 
> Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
> ---
>   drivers/gpu/drm/stm/ltdc.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/stm/ltdc.c b/drivers/gpu/drm/stm/ltdc.c
> index 195de30eb90c..bd603ef5e935 100644
> --- a/drivers/gpu/drm/stm/ltdc.c
> +++ b/drivers/gpu/drm/stm/ltdc.c
> @@ -1024,6 +1024,8 @@ static int ltdc_crtc_init(struct drm_device *ddev, struct drm_crtc *crtc)
>   		return -EINVAL;
>   	}
>   
> +	drm_plane_create_zpos_immutable_property(primary, 0);
> +
>   	ret = drm_crtc_init_with_planes(ddev, crtc, primary, NULL,
>   					&ltdc_crtc_funcs, NULL);
>   	if (ret) {
> @@ -1046,6 +1048,7 @@ static int ltdc_crtc_init(struct drm_device *ddev, struct drm_crtc *crtc)
>   			DRM_ERROR("Can not create overlay plane %d\n", i);
>   			goto cleanup;
>   		}
> +		drm_plane_create_zpos_immutable_property(overlay, i);
>   	}
>   
>   	return 0;
>