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Subject: Re: [PATCH] drm/mediatek: Update the fb property
 mtk_plane_atomic_async_update
From:   Enric Balletbo i Serra <enric.balletbo@collabora.com>
To:     linux-kernel@vger.kernel.org
Cc:     Collabora Kernel ML <kernel@collabora.com>,
        Bibby Hsieh <bibby.hsieh@mediatek.com>, matthias.bgg@gmail.com,
        drinkcat@chromium.org, hsinyi@chromium.org,
        linux-arm-kernel@lists.infradead.org, CK Hu <ck.hu@mediatek.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        dri-devel@lists.freedesktop.org,
        linux-mediatek@lists.infradead.org,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>
References: <20200213120103.823501-1-enric.balletbo@collabora.com>
Message-ID: <7cd36a53-30d9-7efb-4864-78f994268f1b@collabora.com>
Date:   Thu, 13 Feb 2020 14:38:13 +0100
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Hi,

On 13/2/20 13:01, Enric Balletbo i Serra wrote:
> Commit 920fffcc8912 ("drm/mediatek: update cursors by using async atomic
> update") added support to async updates of cursors by using the new atomic
> interface for that. Unfortunately, introduced two issues. The first one is
> that since then, the drm_atomic_helper_async_commit triggers a WARNING due
> current fb is not the new fb. The second one, is that we get a black screen
> connecting the external display on Elm device and another WARNING due vblank
> wait timed out.
> 
> Swap the fb in mtk_plane_atomic_async_update to fix both issues.
> 
> Fixes: 920fffcc8912 ("drm/mediatek: update cursors by using async atomic update")
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
> ---

I just noticed this, which should fix the problem too, so you can ignore this patch.

https://patchwork.kernel.org/patch/11379571/

> 
>  drivers/gpu/drm/mediatek/mtk_drm_plane.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_plane.c b/drivers/gpu/drm/mediatek/mtk_drm_plane.c
> index 914cc7619cd7..7eb10115e72a 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_plane.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_plane.c
> @@ -116,6 +116,7 @@ static void mtk_plane_atomic_async_update(struct drm_plane *plane,
>  	plane->state->src_h = new_state->src_h;
>  	plane->state->src_w = new_state->src_w;
>  	state->pending.async_dirty = true;
> +	swap(plane->state->fb, new_state->fb);
>  
>  	mtk_drm_crtc_async_update(new_state->crtc, plane, new_state);
>  }
>