Re: PROBLEM: NULL pointer dereference in dell_set_arguments() in 4.15

[Alexander Sergeyev]

> To make dell_micmute_led_set() work properly we need to ensure that either WMI 
> or SMM driver is already loaded and initialized.

> From the looks of the call trace dell_micmute_led_set() is called from device 
phase of initialization. Which means that there is a use of dell-laptop 
interface while the module is not initialized (since late_initcall). 
Previously, this led to crashes.

But dell_micmute_led_set() does not touch the module state now, so nothing is 
technically broken; dell-smbios and dell-smbios-smm use subsys_initcall, so 
they are ready. But WMI driver is in the same phase with intel hda, so there 
might be something there.