Atm when the connector is added to the drm_mode_config::connector_list,
the connector may not be fully initialized yet. This is not a problem
for static connectors initialized/added during driver loading, for which
the driver ensures that look-ups via the above list are not possible
until all the connector and other required state is fully initialized
already. It's also not a problem for user space looking up either a
static or dynamic (see what this is below) connector, since this will be
only possible once the connector is registered.
A dynamic - atm only a DP MST - connector can be initialized and added
after the load time initialization is done. Such a connector may be
looked up by in-kernel users once it's added to the connector list. In
particular a hotplug handler could perform a detection on all the
connectors on the list and hence find a connector there which isn't yet
initialized. For instance the connector's helper hooks may be unset,
leading to a NULL dereference while the detect helper calls the
connector's drm_connector_helper_funcs::detect() or detect_ctx()
handler.
To resolve the above issue, add a way for dynamic connectors to
separately initialize the DRM core specific parts of the connector
without adding it to the connector list - by calling the new
drm_connector_dynamic_init() - and to add the connector to the list
later once all the initialization is complete and the connector is
registered - by calling the new drm_connector_dynamic_register().
Adding the above 2 functions was also motivated to make the distinction
of the interface between static and dynamic connectors clearer: Drivers
should manually initialize and register only dynamic connectors (with
the above 2 functions). A driver should only initialize a static
connector (with one of the drm_connector_init*, drmm_connector_init*
functions) while the registration of the connector will be done
automatically by DRM core.
v2: (Jani)
- Let initing DDC as well via drm_connector_init_core().
- Rename __drm_connector_init to drm_connector_init_core_and_add().
v3:
- Rename drm_connector_init_core() to drm_connector_dynamic_init().
(Sima)
- Instead of exporting drm_connector_add(), move adding the connector
to the registration step via a new drm_connector_dynamic_register().
(Sima)
- Update drm_connector_dynamic_init()'s function documentation and the
commit log according to the above changes.
- Update the commit log describing the problematic scenario during
connector detection. (Maxime)
Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
Cc: Simona Vetter <simona@xxxxxxxx>
Cc: Maxime Ripard <mripard@xxxxxxxxxx>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx> (v1)
Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx>
---
drivers/gpu/drm/drm_connector.c | 150 +++++++++++++++++++++++++++-----
include/drm/drm_connector.h | 6 ++
2 files changed, 136 insertions(+), 20 deletions(-)
diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index fc35f47e2849e..a53e5629ba6c1 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -218,11 +218,11 @@ void drm_connector_free_work_fn(struct work_struct *work)
}
}
-static int __drm_connector_init(struct drm_device *dev,
- struct drm_connector *connector,
- const struct drm_connector_funcs *funcs,
- int connector_type,
- struct i2c_adapter *ddc)
+static int drm_connector_init_only(struct drm_device *dev,
+ struct drm_connector *connector,
+ const struct drm_connector_funcs *funcs,
+ int connector_type,
+ struct i2c_adapter *ddc)
{
struct drm_mode_config *config = &dev->mode_config;
int ret;
@@ -273,6 +273,7 @@ static int __drm_connector_init(struct drm_device *dev,
/* provide ddc symlink in sysfs */
connector->ddc = ddc;
+ INIT_LIST_HEAD(&connector->head);
INIT_LIST_HEAD(&connector->global_connector_list_entry);
INIT_LIST_HEAD(&connector->probed_modes);
INIT_LIST_HEAD(&connector->modes);
@@ -288,14 +289,6 @@ static int __drm_connector_init(struct drm_device *dev,
drm_connector_get_cmdline_mode(connector);
- /* We should add connectors at the end to avoid upsetting the connector
- * index too much.
- */
- spin_lock_irq(&config->connector_list_lock);
- list_add_tail(&connector->head, &config->connector_list);
- config->num_connector++;
- spin_unlock_irq(&config->connector_list_lock);
-
if (connector_type != DRM_MODE_CONNECTOR_VIRTUAL &&
connector_type != DRM_MODE_CONNECTOR_WRITEBACK)
drm_connector_attach_edid_property(connector);
@@ -332,6 +325,58 @@ static int __drm_connector_init(struct drm_device *dev,
return ret;
}
+static void drm_connector_add(struct drm_connector *connector)
+{
+ struct drm_device *dev = connector->dev;
+ struct drm_mode_config *config = &dev->mode_config;
+
+ /*
+ * TODO: Change this to a WARN, once all drivers are converted to
+ * call drm_connector_dynamic_init() for MST connectors.
+ */
+ if (!list_empty(&connector->head))
+ return;
+
+ spin_lock_irq(&config->connector_list_lock);
+ list_add_tail(&connector->head, &config->connector_list);
+ config->num_connector++;
+ spin_unlock_irq(&config->connector_list_lock);
+}
+
+static void drm_connector_remove(struct drm_connector *connector)
+{
+ struct drm_device *dev = connector->dev;
+
+ /*
+ * For dynamic connectors drm_connector_cleanup() can call this function
+ * before the connector is registered and added to the list.
+ */
+ if (list_empty(&connector->head))
+ return;
+
+ spin_lock_irq(&dev->mode_config.connector_list_lock);
+ list_del_init(&connector->head);
+ dev->mode_config.num_connector--;
+ spin_unlock_irq(&dev->mode_config.connector_list_lock);
+}
+
+static int drm_connector_init_and_add(struct drm_device *dev,
+ struct drm_connector *connector,
+ const struct drm_connector_funcs *funcs,
+ int connector_type,
+ struct i2c_adapter *ddc)
+{
+ int ret;
+
+ ret = drm_connector_init_only(dev, connector, funcs, connector_type, ddc);
+ if (ret)
+ return ret;
+
+ drm_connector_add(connector);
+
+ return 0;
+}
+
/**
* drm_connector_init - Init a preallocated connector
* @dev: DRM device
@@ -361,10 +406,51 @@ int drm_connector_init(struct drm_device *dev,
if (drm_WARN_ON(dev, !(funcs && funcs->destroy)))
return -EINVAL;
- return __drm_connector_init(dev, connector, funcs, connector_type, NULL);
+ return drm_connector_init_and_add(dev, connector, funcs, connector_type, NULL);
}
EXPORT_SYMBOL(drm_connector_init);
+/**
+ * drm_connector_dynamic_init - Init a preallocated dynamic connector
+ * @dev: DRM device
+ * @connector: the connector to init
+ * @funcs: callbacks for this connector
+ * @connector_type: user visible type of the connector
+ * @ddc: pointer to the associated ddc adapter
+ *
+ * Initialises a preallocated dynamic connector. Connectors should be
+ * subclassed as part of driver connector objects. The connector
+ * structure should not be allocated with devm_kzalloc().
+ *
+ * Drivers should call this for dynamic connectors which can be hotplugged
+ * after drm_dev_register() has been called already, e.g. DP MST connectors.
+ * For all other - static - connectors, drivers should call one of the
+ * drm_connector_init*()/drmm_connector_init*() functions.
+ *
+ * After calling this function the drivers must call
+ * drm_connector_dynamic_register().
+ *
+ * To remove the connector the driver must call drm_connector_unregister()
+ * followed by drm_connector_put(). Putting the last reference will call the
+ * driver's &drm_connector_funcs.destroy hook, which in turn must call
+ * drm_connector_cleanup() and free the connector structure.
+ *
+ * Returns:
+ * Zero on success, error code on failure.
+ */
+int drm_connector_dynamic_init(struct drm_device *dev,
+ struct drm_connector *connector,
+ const struct drm_connector_funcs *funcs,
+ int connector_type,
+ struct i2c_adapter *ddc)
+{
+ if (drm_WARN_ON(dev, !(funcs && funcs->destroy)))
+ return -EINVAL;
+
+ return drm_connector_init_only(dev, connector, funcs, connector_type, ddc);
+}
+EXPORT_SYMBOL(drm_connector_dynamic_init);
+
/**
* drm_connector_init_with_ddc - Init a preallocated connector
* @dev: DRM device
@@ -398,7 +484,7 @@ int drm_connector_init_with_ddc(struct drm_device *dev,
if (drm_WARN_ON(dev, !(funcs && funcs->destroy)))
return -EINVAL;
- return __drm_connector_init(dev, connector, funcs, connector_type, ddc);
+ return drm_connector_init_and_add(dev, connector, funcs, connector_type, ddc);
}
EXPORT_SYMBOL(drm_connector_init_with_ddc);
@@ -442,7 +528,7 @@ int drmm_connector_init(struct drm_device *dev,
if (drm_WARN_ON(dev, funcs && funcs->destroy))
return -EINVAL;
- ret = __drm_connector_init(dev, connector, funcs, connector_type, ddc);
+ ret = drm_connector_init_and_add(dev, connector, funcs, connector_type, ddc);
if (ret)
return ret;
@@ -659,10 +745,8 @@ void drm_connector_cleanup(struct drm_connector *connector)
connector->name = NULL;
fwnode_handle_put(connector->fwnode);
connector->fwnode = NULL;
- spin_lock_irq(&dev->mode_config.connector_list_lock);
- list_del(&connector->head);
- dev->mode_config.num_connector--;
- spin_unlock_irq(&dev->mode_config.connector_list_lock);
+
+ drm_connector_remove(connector);
WARN_ON(connector->state && !connector->funcs->atomic_destroy_state);
if (connector->state && connector->funcs->atomic_destroy_state)
@@ -749,6 +833,32 @@ int drm_connector_register(struct drm_connector *connector)
}
EXPORT_SYMBOL(drm_connector_register);
+/**
+ * drm_connector_dynamic_register - register a dynamic connector
+ * @connector: the connector to register
+ *
+ * Register userspace interfaces for a connector. Only call this for connectors
+ * initialized by calling drm_connector_dynamic_init(). All other connectors
+ * will be registered automatically when calling drm_dev_register().
+ *
+ * When the connector is no longer available the driver must call
+ * drm_connector_unregister().
+ *
+ * Returns:
+ * Zero on success, error code on failure.
+ */
+int drm_connector_dynamic_register(struct drm_connector *connector)
+{
+ /* Was the connector inited already? */
+ if (WARN_ON(!(connector->funcs && connector->funcs->destroy)))
+ return -EINVAL;
+
+ drm_connector_add(connector);
+
+ return drm_connector_register(connector);
+}
+EXPORT_SYMBOL(drm_connector_dynamic_register);
+
/**
* drm_connector_unregister - unregister a connector
* @connector: the connector to unregister
diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
index e3fa43291f449..f766d194221d1 100644
--- a/include/drm/drm_connector.h
+++ b/include/drm/drm_connector.h
@@ -2126,6 +2126,11 @@ int drm_connector_init(struct drm_device *dev,
struct drm_connector *connector,
const struct drm_connector_funcs *funcs,
int connector_type);
+int drm_connector_dynamic_init(struct drm_device *dev,
+ struct drm_connector *connector,
+ const struct drm_connector_funcs *funcs,
+ int connector_type,
+ struct i2c_adapter *ddc);
int drm_connector_init_with_ddc(struct drm_device *dev,
struct drm_connector *connector,
const struct drm_connector_funcs *funcs,
@@ -2147,6 +2152,7 @@ int drmm_connector_hdmi_init(struct drm_device *dev,
unsigned int max_bpc);
void drm_connector_attach_edid_property(struct drm_connector *connector);
int drm_connector_register(struct drm_connector *connector);
+int drm_connector_dynamic_register(struct drm_connector *connector);
void drm_connector_unregister(struct drm_connector *connector);
int drm_connector_attach_encoder(struct drm_connector *connector,
struct drm_encoder *encoder);
--
2.44.2
