linux-kernel - [PATCH v9 09/10] drm/vc4: hdmi: stop rereading EDID in get

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Message-Id: <20241223-drm-bridge-hdmi-connector-v9-9-6ce16bcedb8b@linaro.org>
Date: Mon, 23 Dec 2024 04:59:00 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: 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>, 
 Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>, 
 Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, 
 Phong LE <ple@...libre.com>, Inki Dae <inki.dae@...sung.com>, 
 Seung-Woo Kim <sw0312.kim@...sung.com>, 
 Kyungmin Park <kyungmin.park@...sung.com>, 
 Krzysztof Kozlowski <krzk@...nel.org>, 
 Alim Akhtar <alim.akhtar@...sung.com>, Russell King <linux@...linux.org.uk>, 
 Chun-Kuang Hu <chunkuang.hu@...nel.org>, 
 Philipp Zabel <p.zabel@...gutronix.de>, 
 Matthias Brugger <matthias.bgg@...il.com>, 
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, 
 Sandy Huang <hjc@...k-chips.com>, 
 Heiko Stübner <heiko@...ech.de>, 
 Andy Yan <andy.yan@...k-chips.com>, Alain Volmat <alain.volmat@...s.st.com>, 
 Raphael Gallais-Pou <rgallaispou@...il.com>, 
 Dave Stevenson <dave.stevenson@...pberrypi.com>, 
 Maíra Canal <mcanal@...lia.com>, 
 Raspberry Pi Kernel Maintenance <kernel-list@...pberrypi.com>
Cc: Jani Nikula <jani.nikula@...ux.intel.com>, 
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 linux-sound@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 linux-samsung-soc@...r.kernel.org, linux-mediatek@...ts.infradead.org, 
 linux-rockchip@...ts.infradead.org
Subject: [PATCH v9 09/10] drm/vc4: hdmi: stop rereading EDID in get_modes()

The vc4_hdmi_connector_detect_ctx() via vc4_hdmi_handle_hotplug()
already reads EDID and propagates it to the drm_connector. Stop
rereading EDID as a part of the .get_modes() callback and just update
the list of modes. This matches the behaviour of the i915 driver.

Acked-by: Maxime Ripard <mripard@...nel.org>
Tested-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 21 ---------------------
 1 file changed, 21 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 24199b511f2ee1bc3aa5f4a30e9d3d928d556ff1..5282dd765cc9478361a705dca85f615015b12e8e 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -470,31 +470,10 @@ static int vc4_hdmi_connector_detect_ctx(struct drm_connector *connector,
 
 static int vc4_hdmi_connector_get_modes(struct drm_connector *connector)
 {
-	struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector);
 	struct vc4_dev *vc4 = to_vc4_dev(connector->dev);
-	const struct drm_edid *drm_edid;
 	int ret = 0;
 
-	/*
-	 * NOTE: This function should really take vc4_hdmi->mutex, but doing so
-	 * results in reentrancy issues since cec_s_phys_addr() might call
-	 * .adap_enable, which leads to that funtion being called with our mutex
-	 * held.
-	 *
-	 * Concurrency isn't an issue at the moment since we don't share
-	 * any state with any of the other frameworks so we can ignore
-	 * the lock for now.
-	 */
-
-	drm_edid = drm_edid_read_ddc(connector, vc4_hdmi->ddc);
-	drm_edid_connector_update(connector, drm_edid);
-	cec_s_phys_addr(vc4_hdmi->cec_adap,
-			connector->display_info.source_physical_address, false);
-	if (!drm_edid)
-		return 0;
-
 	ret = drm_edid_connector_add_modes(connector);
-	drm_edid_free(drm_edid);
 
 	if (!vc4->hvs->vc5_hdmi_enable_hdmi_20) {
 		struct drm_device *drm = connector->dev;

-- 
2.39.5