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From: Sebastian Reichel <sebastian.reichel@collabora.com>
To: "Sandy Huang" <hjc@rock-chips.com>,
	"Heiko Stübner" <heiko@sntech.de>, "Andy Yan" <andyshrk@163.com>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"Andrzej Hajda" <andrzej.hajda@intel.com>,
	"Neil Armstrong" <neil.armstrong@linaro.org>,
	"Robert Foss" <rfoss@kernel.org>,
	"Laurent Pinchart" <Laurent.pinchart@ideasonboard.com>,
	"Jonas Karlman" <jonas@kwiboo.se>,
	"Jernej Skrabec" <jernej.skrabec@gmail.com>,
	"Rob Herring" <robh@kernel.org>,
	"Krzysztof Kozlowski" <krzk+dt@kernel.org>,
	"Conor Dooley" <conor+dt@kernel.org>,
	"David Airlie" <airlied@gmail.com>,
	"Simona Vetter" <simona@ffwll.ch>,
	"Dmitry Baryshkov" <dmitry.baryshkov@oss.qualcomm.com>,
	"Luca Ceresoli" <luca.ceresoli@bootlin.com>,
	"Philipp Zabel" <p.zabel@pengutronix.de>
Cc: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>,
	 Damon Ding <damon.ding@rock-chips.com>,
	Dmitry Baryshkov <lumag@kernel.org>,
	 Alexey Charkov <alchark@flipper.net>,
	dri-devel@lists.freedesktop.org,
	 linux-rockchip@lists.infradead.org,
	linux-kernel@vger.kernel.org,  devicetree@vger.kernel.org,
	kernel@collabora.com,  linux-arm-kernel@lists.infradead.org,
	 Sebastian Reichel <sebastian.reichel@collabora.com>,
	 Igor Paunovic <royalnet026@gmail.com>
Subject: [PATCH v12 18/23] drm/bridge: synopsys: dw-dp: Drop useless reservation of first slot
Date: Sat, 14 Nov 2026 06:00:51 +0100	[thread overview]
Message-ID: <20261114-synopsys-dw-dp-improvements-v12-18-d42d3dc5bdd4@collabora.com> (raw)
In-Reply-To: <20261114-synopsys-dw-dp-improvements-v12-0-d42d3dc5bdd4@collabora.com>

The origin of this reservation is unclear, but it is a problem in the
atomic_enable code since it potentially races with the audio SDP
reservation once that feature is added. I suppose it was either meant to
be bitmap_zero(), but that is obviously not needed (and would also be a
problem for audio support) or some left-over development code before the
VSC SDP slot was allocated automatically.

From my tests SDP slot 0 works fine and can be used. If SDP slot 0
really needs to be reserved for some reason, the bit should be set in
the probe function to ensure there are no race conditions.

Tested-by: Igor Paunovic <royalnet026@gmail.com> # Orange Pi 5+
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
---
 drivers/gpu/drm/bridge/synopsys/dw-dp.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
index cd1499ae449e..1ae5c842a782 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
@@ -1712,9 +1712,6 @@ static void dw_dp_bridge_atomic_enable(struct drm_bridge *bridge,
 		return;
 	}
 
-	scoped_guard(mutex, &dp->sdp_lock)
-		set_bit(0, dp->sdp_reg_bank);
-
 	ret = dw_dp_link_enable(dp);
 	if (ret < 0) {
 		dev_err(dp->dev, "failed to enable link: %d\n", ret);

-- 
2.53.0


  parent reply	other threads:[~2026-11-14  5:02 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-14  5:00 [PATCH v12 00/23] Synopsys DisplayPort Controller improvements for Rockchip platforms Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 01/23] drm/bridge: synopsys: dw-dp: Register DP AUX on bridge attach Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 02/23] drm/bridge: synopsys: dw-dp: Fix incorrect resource lifetimes in bind callback Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 03/23] drm/bridge: synopsys: dw-dp: Fix error handling for DP link enablement Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 04/23] drm/bridge: synopsys: dw-dp: Document missing reset line deassert Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 05/23] drm/bridge: synopsys: dw-dp: Add missing mutex cleanups on module removal Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 06/23] drm/bridge: synopsys: dw-dp: Fix AUX transfer timeout race condition Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 07/23] drm/bridge: synopsys: dw-dp: Fix support for short I2C reads Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 08/23] drm/bridge: synopsys: dw-dp: Free output_fmts when none are valid Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 09/23] drm/bridge: synopsys: dw-dp: Support MEDIA_BUS_FMT_FIXED Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 10/23] drm/bridge: synopsys: dw-dp: Add follow-up bridge support Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 11/23] drm/bridge: Add out-of-band HPD notify handler Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 12/23] drm/bridge: synopsys: dw-dp: Support software triggered OOB HPD Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 13/23] drm/rockchip: dw_dp: Implement out-of-band HPD handling Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 14/23] drm/bridge: synopsys: dw-dp: Add Runtime PM support Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 15/23] drm/rockchip: dw_dp: Add runtime " Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 16/23] drm/rockchip: dw_dp: Add system " Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 17/23] drm/bridge: synopsys: dw-dp: Protect sdp_reg_bank from concurrent access Sebastian Reichel
2026-11-14  5:00 ` Sebastian Reichel [this message]
2026-11-14  5:00 ` [PATCH v12 19/23] drm/bridge: synopsys: dw-dp: Clear only enabled SDPs on atomic disable Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 20/23] drm/bridge: synopsys: dw-dp: Use regmap_set_bits in dw_dp_send_sdp Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 21/23] dt-bindings: display: rockchip: dw-dp: Fix sound DAI cells Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 22/23] drm/bridge: synopsys: dw-dp: Add audio support Sebastian Reichel
2026-11-14  5:00 ` [PATCH v12 23/23] drm/bridge: synopsys: dw-dp: Retrain on hotplug with pre-enabled link Sebastian Reichel

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