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References: <20220914140031.18578-1-allen-kh.cheng@mediatek.com>
In-Reply-To: <20220914140031.18578-1-allen-kh.cheng@mediatek.com>
From:   Chun-Kuang Hu <chunkuang.hu@kernel.org>
Date:   Sun, 18 Sep 2022 12:32:22 +0800
Message-ID: <CAAOTY_92F5WgCedZOvg_qtkHLorTCXiWtuGgoJ=9gRryYHi7TQ@mail.gmail.com>
Subject: Re: [PATCH v2] drm: mediatek: Fix display vblank timeout when disable dsi
To:     Allen-KH Cheng <allen-kh.cheng@mediatek.com>
Cc:     Chun-Kuang Hu <chunkuang.hu@kernel.org>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Project_Global_Chrome_Upstream_Group 
        <Project_Global_Chrome_Upstream_Group@mediatek.com>,
        DRI Development <dri-devel@lists.freedesktop.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
        Xinlei Lee <xinlei.lee@mediatek.com>
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Hi, Allen:

Allen-KH Cheng <allen-kh.cheng@mediatek.com> =E6=96=BC 2022=E5=B9=B49=E6=9C=
=8814=E6=97=A5 =E9=80=B1=E4=B8=89 =E6=99=9A=E4=B8=8A10:00=E5=AF=AB=E9=81=93=
=EF=BC=9A
>
> From: Xinlei Lee <xinlei.lee@mediatek.com>
>
> Dsi is turned off at bridge.disable, causing crtc to wait for vblank
> timeout. It is necessary to add count protection to turn off dsi and
> turn off at post_disable.

If turn off dsi in post_disable(), you should turn on dsi in pre_enable().

There is another patch fix this problem [1], do you have any comment
on that patch?

[1] http://lists.infradead.org/pipermail/linux-mediatek/2022-August/046713.=
html

Regards,
Chun-Kuang.

>
> Fixes: cde7e2e35c28 ("drm/mediatek: Separate poweron/poweroff from enable=
/disable and define new funcs")
> Signed-off-by: Xinlei Lee <xinlei.lee@mediatek.com>
> Co-developed-by: Allen-KH Cheng <allen-kh.cheng@mediatek.com>
> Signed-off-by: Allen-KH Cheng <allen-kh.cheng@mediatek.com>
> ---
> Change in v1:
>   * Rebase to kernel/git/chunkuang.hu/linux.git, mediatek-drm-fixes
>     [Allen-KH Cheng <allen-kh.cheng@mediatek.com>]
> ---
> ---
>  drivers/gpu/drm/mediatek/mtk_dsi.c | 15 ++++++---------
>  1 file changed, 6 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediate=
k/mtk_dsi.c
> index 5b624e0f5b0a..e30f4244c001 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -768,14 +768,6 @@ static void mtk_dsi_bridge_mode_set(struct drm_bridg=
e *bridge,
>         drm_display_mode_to_videomode(adjusted, &dsi->vm);
>  }
>
> -static void mtk_dsi_bridge_atomic_disable(struct drm_bridge *bridge,
> -                                         struct drm_bridge_state *old_br=
idge_state)
> -{
> -       struct mtk_dsi *dsi =3D bridge_to_dsi(bridge);
> -
> -       mtk_output_dsi_disable(dsi);
> -}
> -
>  static void mtk_dsi_bridge_atomic_enable(struct drm_bridge *bridge,
>                                          struct drm_bridge_state *old_bri=
dge_state)
>  {
> @@ -803,13 +795,15 @@ static void mtk_dsi_bridge_atomic_post_disable(stru=
ct drm_bridge *bridge,
>  {
>         struct mtk_dsi *dsi =3D bridge_to_dsi(bridge);
>
> +       if (dsi->refcount =3D=3D 1)
> +               mtk_output_dsi_disable(dsi);
> +
>         mtk_dsi_poweroff(dsi);
>  }
>
>  static const struct drm_bridge_funcs mtk_dsi_bridge_funcs =3D {
>         .attach =3D mtk_dsi_bridge_attach,
>         .atomic_destroy_state =3D drm_atomic_helper_bridge_destroy_state,
> -       .atomic_disable =3D mtk_dsi_bridge_atomic_disable,
>         .atomic_duplicate_state =3D drm_atomic_helper_bridge_duplicate_st=
ate,
>         .atomic_enable =3D mtk_dsi_bridge_atomic_enable,
>         .atomic_pre_enable =3D mtk_dsi_bridge_atomic_pre_enable,
> @@ -829,6 +823,9 @@ void mtk_dsi_ddp_stop(struct device *dev)
>  {
>         struct mtk_dsi *dsi =3D dev_get_drvdata(dev);
>
> +       if (dsi->refcount =3D=3D 1)
> +               mtk_output_dsi_disable(dsi);
> +
>         mtk_dsi_poweroff(dsi);
>  }
>
> --
> 2.18.0
>