linux-kernel - Re: [PATCH v2 1/3] drm/mediatek: dsi: Reduce the time of dsi from LP11 to sending cmd

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Message-ID: <CAAOTY__wuHgZmPKGxKPceHTcupUqKyxPb0CrG=ZB1c47T+Dohg@mail.gmail.com>
Date:   Fri, 27 Jan 2023 08:12:47 +0800
From:   Chun-Kuang Hu <chunkuang.hu@...nel.org>
To:     xinlei.lee@...iatek.com
Cc:     chunkuang.hu@...nel.org, p.zabel@...gutronix.de, airlied@...ux.ie,
        daniel@...ll.ch, matthias.bgg@...il.com,
        angelogioacchino.delregno@...labora.com, jitao.shi@...iatek.com,
        thierry.reding@...il.com, sam@...nborg.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Project_Global_Chrome_Upstream_Group@...iatek.com
Subject: Re: [PATCH v2 1/3] drm/mediatek: dsi: Reduce the time of dsi from
 LP11 to sending cmd

Hi, Xinlei:

<xinlei.lee@...iatek.com> 於 2023年1月10日 週二 下午1:55寫道：
>
> From: Xinlei Lee <xinlei.lee@...iatek.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=mediatek-drm-next

Regards,
Chun-Kuang.

>
> [1]:mipi_D-PHY_specification_v1-1
>
> Fixes: 39e8d062b03c ("drm/mediatek: Keep dsi as LP00 before dcs cmds transfer")
> Signed-off-by: Xinlei Lee <xinlei.lee@...iatek.com>
> Acked-by: Sam Ravnborg <sam@...nborg.org>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.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/mediatek/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
>