linux-kernel - [PATCH 1/3] drm/bridge: it6505: Initialize AUX channel in it6505_i2c

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Message-Id: <20221012162900.2876686-2-treapking@chromium.org>
Date:   Thu, 13 Oct 2022 00:28:57 +0800
From:   Pin-yen Lin <treapking@...omium.org>
To:     Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     Pin-yen Lin <treapking@...omium.org>,
        Allen Chen <allen.chen@....com.tw>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Hermes Wu <hermes.wu@....com.tw>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/3] drm/bridge: it6505: Initialize AUX channel in it6505_i2c_probe

During device boot, the HPD interrupt could be triggered before the DRM
subsystem registers it6505 as a DRM bridge. In such cases, the driver
tries to access AUX channel and causes NULL pointer dereference.
Initializing the AUX channel earlier to prevent such error.

Fixes: b5c84a9edcd4 ("drm/bridge: add it6505 driver")
Signed-off-by: Pin-yen Lin <treapking@...omium.org>
---

 drivers/gpu/drm/bridge/ite-it6505.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index a4302492cf8d..f7f6c3e20fae 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -2871,10 +2871,7 @@ static int it6505_bridge_attach(struct drm_bridge *bridge,
 	}
 
 	/* Register aux channel */
-	it6505->aux.name = "DP-AUX";
-	it6505->aux.dev = dev;
 	it6505->aux.drm_dev = bridge->dev;
-	it6505->aux.transfer = it6505_aux_transfer;
 
 	ret = drm_dp_aux_register(&it6505->aux);
 
@@ -3354,6 +3351,11 @@ static int it6505_i2c_probe(struct i2c_client *client,
 	debugfs_init(it6505);
 	pm_runtime_enable(dev);
 
+	it6505->aux.name = "DP-AUX";
+	it6505->aux.dev = dev;
+	it6505->aux.transfer = it6505_aux_transfer;
+	drm_dp_aux_init(&it6505->aux);
+
 	it6505->bridge.funcs = &it6505_bridge_funcs;
 	it6505->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
 	it6505->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID |
-- 
2.38.0.rc1.362.ged0d419d3c-goog