linux-kernel - [PATCH 1/3] drm/bridge: samsung-dsim: move bridge init sequence to atomic

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Message-Id: <20260124-exynos-dsim-fixes-v1-1-122d047a23d1@disroot.org>
Date: Sat, 24 Jan 2026 22:50:46 +0530
From: Kaustabh Chakraborty <kauschluss@...root.org>
To: Inki Dae <inki.dae@...sung.com>, 
 Jagan Teki <jagan@...rulasolutions.com>, 
 Marek Szyprowski <m.szyprowski@...sung.com>, 
 Andrzej Hajda <andrzej.hajda@...el.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>
Cc: dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Kaustabh Chakraborty <kauschluss@...root.org>, stable@...r.kernel.org
Subject: [PATCH 1/3] drm/bridge: samsung-dsim: move bridge init sequence to
 atomic_enable

Since commit c9b1150a68d9 ("drm/atomic-helper: Re-order bridge chain
pre-enable and post-disable"), pre-enable sequence is called before the
CRTC is enabled.

This causes unintended side-effects (abberation among potentially other
things) in the display when samsung_dsim_init() is called in the
pre-enable part of the sequence. Call it in samsung_dsim_atomic_enable()
instead.

Cc: stable@...r.kernel.org # v6.17 and later
Signed-off-by: Kaustabh Chakraborty <kauschluss@...root.org>
---
 drivers/gpu/drm/bridge/samsung-dsim.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c b/drivers/gpu/drm/bridge/samsung-dsim.c
index 1d85e706c74b9..975f8b50ae660 100644
--- a/drivers/gpu/drm/bridge/samsung-dsim.c
+++ b/drivers/gpu/drm/bridge/samsung-dsim.c
@@ -1655,6 +1655,13 @@ static void samsung_dsim_atomic_pre_enable(struct drm_bridge *bridge,
 	}
 
 	dsi->state |= DSIM_STATE_ENABLED;
+}
+
+static void samsung_dsim_atomic_enable(struct drm_bridge *bridge,
+				       struct drm_atomic_state *state)
+{
+	struct samsung_dsim *dsi = bridge_to_dsi(bridge);
+	int ret;
 
 	/*
 	 * For Exynos-DSIM the downstream bridge, or panel are expecting
@@ -1665,12 +1672,6 @@ static void samsung_dsim_atomic_pre_enable(struct drm_bridge *bridge,
 		if (ret)
 			return;
 	}
-}
-
-static void samsung_dsim_atomic_enable(struct drm_bridge *bridge,
-				       struct drm_atomic_state *state)
-{
-	struct samsung_dsim *dsi = bridge_to_dsi(bridge);
 
 	samsung_dsim_set_display_mode(dsi);
 	samsung_dsim_set_display_enable(dsi, true);

-- 
2.52.0