linux-kernel - Re: [PATCH v4 11/15] drm/mediatek: dsi: Improves the DSI lane setup robustness

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Date: Thu, 27 Jun 2024 22:31:55 +0800
From: Chun-Kuang Hu <chunkuang.hu@...nel.org>
To: Alexandre Mergnat <amergnat@...libre.com>, Shuijing Li <shuijing.li@...iatek.com>
Cc: Chun-Kuang Hu <chunkuang.hu@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Matthias Brugger <matthias.bgg@...il.com>, 
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
	Jitao Shi <jitao.shi@...iatek.com>, CK Hu <ck.hu@...iatek.com>, 
	Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
	dri-devel@...ts.freedesktop.org, linux-mediatek@...ts.infradead.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 11/15] drm/mediatek: dsi: Improves the DSI lane setup robustness

Hi, Shuijing:

Please help to review this patch.

Regards,
Chun-Kuang.

Alexandre Mergnat <amergnat@...libre.com> 於 2024年5月23日 週四 下午8:49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 e036d9394c23..cb546a9e9419 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -643,6 +643,8 @@ 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);
>
> --
> 2.25.1
>