In a situation when the reference count of the drm connector is greater than 1,
the unbind function should not invoke drm_connector_cleanup as this will lead
to an inconsistent state where the drm_crtc_state->connector_mask still has
a bitmask referring to the stale connector. Later, when drm driver invokes
drm_atomic_helper_shutdown() which invokes ---> drm_atomic_helper_disable_all()
---> drm_atomic_commit() --> drm_atomic_check_only() -->
drm_atomic_helper_check() --> drm_atomic_helper_check_modeset(). This returns
an error due to enabled/connectors mismatch.
In such a scenario, one should just return from _unbind() and let the drm driver
subsequently invoke drm_atomic_helper_shutdown. This will reset the
drm_crtc_state->connector_mask and will shutdown the crtcs. It will also decrement
the reference count of the connectors to 1. Subsequently, drm_mode_config_cleanup
will get invoked which will do the following :-
1. Decrement the reference count for each of the connectors. Thus the ref count
will reach 0 and drm_connector_funcs->destroy() gets called. Thus,
tda998x_connector_destroy() gets invoked which calls drm_connector_cleanup
2. Invokes the destroy callback for each encoder. Thus tda998x_encoder_destroy()
gets invoked.
Signed-off-by: Ayan Kumar Halder <ayan.halder@xxxxxxx>
---
drivers/gpu/drm/i2c/tda998x_drv.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
index 9e67a7b..8ad1cc7 100644
--- a/drivers/gpu/drm/i2c/tda998x_drv.c
+++ b/drivers/gpu/drm/i2c/tda998x_drv.c
@@ -1709,6 +1709,9 @@ static void tda998x_unbind(struct device *dev, struct device *master,
{
struct tda998x_priv *priv = dev_get_drvdata(dev);
+ if (kref_read(&priv->connector.base.refcount) > 1)
+ return;
+
drm_connector_cleanup(&priv->connector);
drm_encoder_cleanup(&priv->encoder);
tda998x_destroy(priv);
--
2.7.4
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