drm/bridge: it6505: Initialize AUX channel in it6505_i2c_probe

[ Upstream commit e577d4b13064c337b83fe7edecb3f34e87144821 ]

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@chromium.org>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20221013110411.1674359-2-treapking@chromium.org
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index dfe4351..99123ee 100644 (file)
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -2860,10 +2860,7 @@ 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);
 
@@ -3316,6 +3313,11 @@ static int it6505_i2c_probe(struct i2c_client *client,
        DRM_DEV_DEBUG_DRIVER(dev, "it6505 device name: %s", dev_name(dev));
        debugfs_init(it6505);
 
+       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 |