drm/gma500/oaktrail_lvds: fix hang on init failure

commit 657a091ab6d01d0091b77660c75cfed573c9a53e upstream.

The LVDS init code looks up an I2C adapter using i2c_get_adapter() and
tries to read the EDID before falling back to allocating and registering
its own adapter.

The error handling does not separate these cases so on a late init
failure it will try to deregister and free also an adapter that had
previously been registered. Since i2c_get_adapter() takes another
reference to the adapter, deregistration hangs indefinitely while
waiting for the reference to be released.

Fix this by only destroying adapters allocated during LVDS init on
errors.

Fixes: a57ebfc ("drm/gma500: Make oaktrail lvds use ddc adapter from drm_connector")
Cc: stable@vger.kernel.org	# 6.0
Cc: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Link: https://patch.msgid.link/20260508144446.59722-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: jhovold

drivers/gpu/drm/gma500/oaktrail_lvds.c

@@ -292,7 +292,7 @@ void oaktrail_lvds_init(struct drm_device *dev,
 {
 	struct gma_encoder *gma_encoder;
 	struct gma_connector *gma_connector;
-	struct gma_i2c_chan *ddc_bus;
+	struct gma_i2c_chan *ddc_bus = NULL;
 	struct drm_connector *connector;
 	struct drm_encoder *encoder;
 	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
@@ -420,7 +420,8 @@ void oaktrail_lvds_init(struct drm_device *dev,
 
 err_unlock:
 	mutex_unlock(&dev->mode_config.mutex);
-	gma_i2c_destroy(to_gma_i2c_chan(connector->ddc));
+	if (!IS_ERR_OR_NULL(ddc_bus))
+		gma_i2c_destroy(ddc_bus);
 	drm_encoder_cleanup(encoder);
 err_connector_cleanup:
 	drm_connector_cleanup(connector);