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From: Alexandre Mergnat <amergnat@baylibre.com>
Date: Thu, 18 Apr 2024 16:17:01 +0200
Subject: [PATCH v3 13/17] drm/mediatek: dsi: Improves the DSI lane setup
 robustness
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To: Chun-Kuang Hu <chunkuang.hu@kernel.org>, 
 Philipp Zabel <p.zabel@pengutronix.de>, 
 Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, 
 Maxime Ripard <mripard@kernel.org>, Thomas Zimmermann <tzimmermann@suse.de>, 
 David Airlie <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>, 
 Rob Herring <robh@kernel.org>, 
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, 
 Conor Dooley <conor+dt@kernel.org>, 
 Matthias Brugger <matthias.bgg@gmail.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>, 
 Jitao Shi <jitao.shi@mediatek.com>, CK Hu <ck.hu@mediatek.com>, 
 =?utf-8?q?Uwe_Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>, 
 Michael Turquette <mturquette@baylibre.com>, 
 Stephen Boyd <sboyd@kernel.org>, Fabien Parent <fparent@baylibre.com>, 
 Markus Schneider-Pargmann <msp@baylibre.com>, 
 Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>
Cc: dri-devel@lists.freedesktop.org, linux-mediatek@lists.infradead.org, 
 devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, 
 linux-arm-kernel@lists.infradead.org, linux-pwm@vger.kernel.org, 
 linux-clk@vger.kernel.org, Alexandre Mergnat <amergnat@baylibre.com>

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@baylibre.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 9501f4019199..b3f33d4d3d5c 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -642,6 +642,8 @@ 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