linux-kernel - Re: [PATCH 18/21] drm/mediatek: dsi: Improves the DSI lane setup robustness

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Date:   Mon, 27 Mar 2023 23:37:47 +0800
From:   Chun-Kuang Hu <chunkuang.hu@...nel.org>
To:     Alexandre Mergnat <amergnat@...libre.com>
Cc:     Daniel Vetter <daniel@...ll.ch>, CK Hu <ck.hu@...iatek.com>,
        Jitao Shi <jitao.shi@...iatek.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Sam Ravnborg <sam@...nborg.org>,
        Rob Herring <robh+dt@...nel.org>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        David Airlie <airlied@...il.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Xinlei Lee <xinlei.lee@...iatek.com>,
        Guillaume La Roque <glaroque@...libre.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        dri-devel@...ts.freedesktop.org,
        Fabien Parent <fparent@...libre.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 18/21] drm/mediatek: dsi: Improves the DSI lane setup robustness

Hi, Xinlei:

Could you help to review this patch?

Regards,
Chun-Kuang.

Alexandre Mergnat <amergnat@...libre.com> 於 2023年3月9日 週四 下午10:23寫道：
>
> Currently, mtk_dsi_lane_ready (which setup the DSI lane) is triggered
> before mtk_dsi_poweron. lanes_ready flag toggle to true during
> mtk_dsi_lane_ready function, and the DSI module is set up during
> mtk_dsi_poweron.
>
> Later, during panel driver init, mtk_dsi_lane_ready is triggered but does
> nothing because lanes are considered ready. Unfortunately, when the panel
> driver try to communicate, the DSI returns a timeout.
>
> The solution found here is to put lanes_ready flag to false after the DSI
> module setup into mtk_dsi_poweron to init the DSI lanes after the power /
> setup of the DSI module.
>
> Signed-off-by: Alexandre Mergnat <amergnat@...libre.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_dsi.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
> index 3b7d13028fb6..35c36cc05c04 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -667,6 +667,8 @@ static int mtk_dsi_poweron(struct mtk_dsi *dsi)
>         mtk_dsi_config_vdo_timing(dsi);
>         mtk_dsi_set_interrupt_enable(dsi);
>
> +       dsi->lanes_ready = false;
> +
>         return 0;
>  err_disable_engine_clk:
>         clk_disable_unprepare(dsi->engine_clk);
>
> --
> b4 0.10.1