1 files changed, 35 insertions, 18 deletions

diff --git a/drivers/platform/surface/aggregator/controller.c b/drivers/platform/surface/aggregator/controller.c
index b8c377b3f932..6de834b52b63 100644
--- a/drivers/platform/surface/aggregator/controller.c
+++ b/drivers/platform/surface/aggregator/controller.c
@@ -2199,16 +2199,26 @@ static int ssam_nf_refcount_enable(struct ssam_controller *ctrl,
 }
 
 /**
- * ssam_nf_refcount_disable_free() - Disable event for reference count entry if it is
- * no longer in use and free the corresponding entry.
+ * ssam_nf_refcount_disable_free() - Disable event for reference count entry if
+ * it is no longer in use and free the corresponding entry.
  * @ctrl:  The controller to disable the event on.
  * @entry: The reference count entry for the event to be disabled.
  * @flags: The flags used for enabling the event on the EC.
+ * @ec:    Flag specifying if the event should actually be disabled on the EC.
  *
- * If the reference count equals zero, i.e. the event is no longer requested by
- * any client, the event will be disabled and the corresponding reference count
- * entry freed. The reference count entry must not be used any more after a
- * call to this function.
+ * If ``ec`` equals ``true`` and the reference count equals zero (i.e. the
+ * event is no longer requested by any client), the specified event will be
+ * disabled on the EC via the corresponding request.
+ *
+ * If ``ec`` equals ``false``, no request will be sent to the EC and the event
+ * can be considered in a detached state (i.e. no longer used but still
+ * enabled). Disabling an event via this method may be required for
+ * hot-removable devices, where event disable requests may time out after the
+ * device has been physically removed.
+ *
+ * In both cases, if the reference count equals zero, the corresponding
+ * reference count entry will be freed. The reference count entry must not be
+ * used any more after a call to this function.
  *
  * Also checks if the flags used for disabling the event match the flags used
  * for enabling the event and warns if they do not (regardless of reference
@@ -2223,7 +2233,7 @@ static int ssam_nf_refcount_enable(struct ssam_controller *ctrl,
  * returns the status of the event-enable EC command.
  */
 static int ssam_nf_refcount_disable_free(struct ssam_controller *ctrl,
-					 struct ssam_nf_refcount_entry *entry, u8 flags)
+					 struct ssam_nf_refcount_entry *entry, u8 flags, bool ec)
 {
 	const struct ssam_event_registry reg = entry->key.reg;
 	const struct ssam_event_id id = entry->key.id;
@@ -2232,8 +2242,9 @@ static int ssam_nf_refcount_disable_free(struct ssam_controller *ctrl,
 
 	lockdep_assert_held(&nf->lock);
 
-	ssam_dbg(ctrl, "disabling event (reg: %#04x, tc: %#04x, iid: %#04x, rc: %d)\n",
-		 reg.target_category, id.target_category, id.instance, entry->refcount);
+	ssam_dbg(ctrl, "%s event (reg: %#04x, tc: %#04x, iid: %#04x, rc: %d)\n",
+		 ec ? "disabling" : "detaching", reg.target_category, id.target_category,
+		 id.instance, entry->refcount);
 
 	if (entry->flags != flags) {
 		ssam_warn(ctrl,
@@ -2242,7 +2253,7 @@ static int ssam_nf_refcount_disable_free(struct ssam_controller *ctrl,
 			  id.instance);
 	}
 
-	if (entry->refcount == 0) {
+	if (ec && entry->refcount == 0) {
 		status = ssam_ssh_event_disable(ctrl, reg, id, flags);
 		kfree(entry);
 	}
@@ -2322,20 +2333,26 @@ int ssam_notifier_register(struct ssam_controller *ctrl, struct ssam_event_notif
 EXPORT_SYMBOL_GPL(ssam_notifier_register);
 
 /**
- * ssam_notifier_unregister() - Unregister an event notifier.
- * @ctrl: The controller the notifier has been registered on.
- * @n:    The event notifier to unregister.
+ * __ssam_notifier_unregister() - Unregister an event notifier.
+ * @ctrl:    The controller the notifier has been registered on.
+ * @n:       The event notifier to unregister.
+ * @disable: Whether to disable the corresponding event on the EC.
  *
  * Unregister an event notifier. Decrement the usage counter of the associated
  * SAM event if the notifier is not marked as an observer. If the usage counter
- * reaches zero, the event will be disabled.
+ * reaches zero and ``disable`` equals ``true``, the event will be disabled.
+ *
+ * Useful for hot-removable devices, where communication may fail once the
+ * device has been physically removed. In that case, specifying ``disable`` as
+ * ``false`` avoids communication with the EC.
  *
  * Return: Returns zero on success, %-ENOENT if the given notifier block has
  * not been registered on the controller. If the given notifier block was the
  * last one associated with its specific event, returns the status of the
  * event-disable EC-command.
  */
-int ssam_notifier_unregister(struct ssam_controller *ctrl, struct ssam_event_notifier *n)
+int __ssam_notifier_unregister(struct ssam_controller *ctrl, struct ssam_event_notifier *n,
+			       bool disable)
 {
 	u16 rqid = ssh_tc_to_rqid(n->event.id.target_category);
 	struct ssam_nf_refcount_entry *entry;
@@ -2373,7 +2390,7 @@ int ssam_notifier_unregister(struct ssam_controller *ctrl, struct ssam_event_not
 			goto remove;
 		}
 
-		status = ssam_nf_refcount_disable_free(ctrl, entry, n->event.flags);
+		status = ssam_nf_refcount_disable_free(ctrl, entry, n->event.flags, disable);
 	}
 
 remove:
@@ -2383,7 +2400,7 @@ remove:
 
 	return status;
 }
-EXPORT_SYMBOL_GPL(ssam_notifier_unregister);
+EXPORT_SYMBOL_GPL(__ssam_notifier_unregister);
 
 /**
  * ssam_controller_event_enable() - Enable the specified event.
@@ -2477,7 +2494,7 @@ int ssam_controller_event_disable(struct ssam_controller *ctrl,
 		return -ENOENT;
 	}
 
-	status = ssam_nf_refcount_disable_free(ctrl, entry, flags);
+	status = ssam_nf_refcount_disable_free(ctrl, entry, flags, true);
 
 	mutex_unlock(&nf->lock);
 	return status;