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From:   Chun-Kuang Hu <chunkuang.hu@kernel.org>
Date:   Thu, 22 Oct 2020 01:07:04 +0800
Message-ID: <CAAOTY_9Y98yHq7GcypUMryG4jMEdrDJeCeRXEKX3mb5g39y+sg@mail.gmail.com>
Subject: Re: [PATCH 4/8] drm/mediatek: dsi: add pdata variable to start clk in
 HS mode
To:     Fabien Parent <fparent@baylibre.com>
Cc:     "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@lists.infradead.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        DTML <devicetree@vger.kernel.org>,
        DRI Development <dri-devel@lists.freedesktop.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        David Airlie <airlied@linux.ie>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Chun-Kuang Hu <chunkuang.hu@kernel.org>
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Hi, Fabien:

Fabien Parent <fparent@baylibre.com> =E6=96=BC 2020=E5=B9=B410=E6=9C=8821=
=E6=97=A5 =E9=80=B1=E4=B8=89 =E4=B8=8A=E5=8D=881:43=E5=AF=AB=E9=81=93=EF=BC=
=9A
>
> On MT8167, DSI seems to work fine only if we start the clk in HS mode.
> If we don't start the clk in HS but try to switch later to HS, the
> display does not work.
>
> This commit adds a platform data variable to be used to start the
> DSI clk in HS mode at power on.

This patch looks like a hack patch. If you cowork with Mediatek,
please find out the correct solution or give a reasonable explanation.
If you could not get help from Mediatek, I would wait for comment on
this patch.

Regards,
Chun-Kuang.

>
> Signed-off-by: Fabien Parent <fparent@baylibre.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dsi.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediate=
k/mtk_dsi.c
> index 4a188a942c38..461643c05689 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -175,6 +175,7 @@ struct mtk_dsi_driver_data {
>         const u32 reg_cmdq_off;
>         bool has_shadow_ctl;
>         bool has_size_ctl;
> +       bool use_hs_on_power_on;
>  };
>
>  struct mtk_dsi {
> @@ -671,7 +672,7 @@ static int mtk_dsi_poweron(struct mtk_dsi *dsi)
>
>         mtk_dsi_clk_ulp_mode_leave(dsi);
>         mtk_dsi_lane0_ulp_mode_leave(dsi);
> -       mtk_dsi_clk_hs_mode(dsi, 0);
> +       mtk_dsi_clk_hs_mode(dsi, !!dsi->driver_data->use_hs_on_power_on);
>
>         return 0;
>  err_disable_engine_clk:
> --
> 2.28.0
>