On 4/20/22 21:47, Rafael J. Wysocki wrote:
+/**
+ * devm_register_prioritized_power_off_handler - Register prioritized power-off callback
+ * @dev: Device that registers callback
+ * @priority: Callback's priority
+ * @callback: Callback function
+ * @cb_data: Callback's argument
+ *
+ * Registers resource-managed power-off callback with a given priority.
+ * It will be called as last step of the power-off sequence. Callbacks
+ * chaining is disabled, i.e. further lower priority callbacks won't
+ * be executed if this @callback will fail to execute.
+ *
+ * Returns zero on success, or error code on failure.
What's the case in which this should be used instead of registering a
full sys_off handler?
There are a lot of drivers that just want to register power-off handler
with a non-default priority and don't need to stop the chain or do
anything else special. This is a convinient helper for them.
Please note that the callback here takes only the cb_data for the
argument, while sys_off uses "struct power_off_data".
Similar for the reset of the convinient helpers.
So if there is a way to do this, why would anyone prefer to use the
full sys_off handler at all?
There are couple occurrences around kernel where there is no device
available for the devm_ functions, like this for example [1].
[1]
https://gitlab.collabora.com/dmitry.osipenko/linux-kernel-rd/-/commit/184dfd3983e774d3cf9050dc5b4ec23a662a9551
--
Best regards,
Dmitry
