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In-Reply-To: <1673330093-6771-2-git-send-email-xinlei.lee@mediatek.com>
From:   Chun-Kuang Hu <chunkuang.hu@kernel.org>
Date:   Fri, 27 Jan 2023 08:12:47 +0800
Message-ID: <CAAOTY__wuHgZmPKGxKPceHTcupUqKyxPb0CrG=ZB1c47T+Dohg@mail.gmail.com>
Subject: Re: [PATCH v2 1/3] drm/mediatek: dsi: Reduce the time of dsi from
 LP11 to sending cmd
To:     xinlei.lee@mediatek.com
Cc:     chunkuang.hu@kernel.org, p.zabel@pengutronix.de, airlied@linux.ie,
        daniel@ffwll.ch, matthias.bgg@gmail.com,
        angelogioacchino.delregno@collabora.com, jitao.shi@mediatek.com,
        thierry.reding@gmail.com, sam@ravnborg.org,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org,
        Project_Global_Chrome_Upstream_Group@mediatek.com
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Hi, Xinlei:

<xinlei.lee@mediatek.com> =E6=96=BC 2023=E5=B9=B41=E6=9C=8810=E6=97=A5 =E9=
=80=B1=E4=BA=8C =E4=B8=8B=E5=8D=881:55=E5=AF=AB=E9=81=93=EF=BC=9A
>
> From: Xinlei Lee <xinlei.lee@mediatek.com>
>
> According to Figure 16 Turnaround Procedure on page 36 in [1], you
> can see the status of LP-00 -> LP10 -> LP11. This state can correspond
> to the state of DSI from LP00 -> LP11 in mtk_dsi_lane_ready function
> in mtk_dsi.c.
>
> LP-00 -> LP10 -> LP11 takes about 2*TLPX time (refer to [1] page 51
> to see that TLPX is 50ns)
>
> The delay at the end of the mtk_dsi_lane_ready function should be
> greater than the 2*TLPX specified by the DSI spec, and less than
> the time specified by the DSI_RX (generally 6ms to 40ms), to avoid
> problems caused by the RX specification

Applied to mediatek-drm-next [1], thanks.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/=
log/?h=3Dmediatek-drm-next

Regards,
Chun-Kuang.

>
> [1]:mipi_D-PHY_specification_v1-1
>
> Fixes: 39e8d062b03c ("drm/mediatek: Keep dsi as LP00 before dcs cmds tran=
sfer")
> Signed-off-by: Xinlei Lee <xinlei.lee@mediatek.com>
> Acked-by: Sam Ravnborg <sam@ravnborg.org>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collab=
ora.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dsi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediate=
k/mtk_dsi.c
> index 3b7d13028fb6..9e1363c9fcdb 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -721,7 +721,7 @@ static void mtk_dsi_lane_ready(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);
> -               msleep(20);
> +               usleep_range(1000, 3000);
>                 /* The reaction time after pulling up the mipi signal for=
 dsi_rx */
>         }
>  }
> --
> 2.18.0
>