[PATCH 2/3] drm/gma500/oaktrail_lvds: fix hang on init failure

[Johan Hovold]

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: a57ebfc0b4da ("drm/gma500: Make oaktrail lvds use ddc adapter from drm_connector")
Cc: stable@xxxxxxxxxxxxxxx	# 6.0
Cc: Patrik Jakobsson <patrik.r.jakobsson@xxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
---
 drivers/gpu/drm/gma500/oaktrail_lvds.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/gma500/oaktrail_lvds.c b/drivers/gpu/drm/gma500/oaktrail_lvds.c
index 884d324f0044..983cc60a1e69 100644
--- a/drivers/gpu/drm/gma500/oaktrail_lvds.c
+++ b/drivers/gpu/drm/gma500/oaktrail_lvds.c
@@ -293,7 +293,7 @@ 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);
@@ -421,7 +421,8 @@ 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);
-- 
2.53.0