Re: [PATCH v2 2/4] platform: x86: dell-smbios: Add a generic dell-smbios notifier chain

["Pali Rohár" <pali.rohar@gmail.com>]

On Monday 24 October 2016 15:45:02 Hans de Goede wrote:
> Hi,
> 
> On 24-10-16 15:43, Pali Rohár wrote:
> >On Monday 24 October 2016 15:37:31 Hans de Goede wrote:
> >>Well WMI events get enabled via a SMBIOS call,
> >
> >This is truth only for few laptops and only for one WMI event.
> >Everything else is automatically enabled, no call is needed to issue.
> >
> >>and dell-laptop uses SMBIOS exclusively
> >
> >IIRC dell-led.ko uses also dell-smbio.ko, so it is not exclusive for
> >dell-laptop.
> >
> >>so it seems to fit. Basically this is a case of
> >>we have to put this somewhere and dell-smbios is the best fit IMHO.
> >
> >Agree, we need to put it somewhere...
> >
> >Basically we need to solve problem how (currently) 3 kernel modules can
> >communicate. Does not kernel support such "bus/event" mechanism for
> >this?
> 
> Yes it does, that is exactly what notifiers are for, but we need to
> declare the bus somewhere. I still believe dell-smbios is the best
> place.

But dell_smbios_register_notifier() name is totally confusing. It does
not register any notifier for SMBIOS. Nor it have nothing common with
SMBIOS API.

Also there is absolutely no need that dell-rbtn.ko needs to depends on
dell-smbios.ko. dell-rbtn.ko is ACPI driver which does not use any of
SMBIOS API.

Right now I'm not saying what is the best place for that notifier (as I
still do not have ideal candidate). I'm just saying that notifier is not
part of SMBIOS API and therefore dell-smbios.ko is not right place for
it.

So currently we have these different APIs for dell notebook drivers:
* ACPI (used in dell-rbtn.ko and dell-smo8800.ko)
* WMI (used in dell-wmi.ko, dell-wmi-aio.ko, dell-led.ko)
* SMBIOS (used in dell-laptop.ko, dell-wmi.ko and dell-led.ko)
* some other platform code (used in dell-laptop.ko)

And now notifier is needed for drivers:
* dell-laptop.ko
* dell-wmi.ko
* dell-rbtn.ko

And if I look at above two sets, none of above drivers is good candidate
for central notifier functions... Maybe we should really introduce new
separate file where will central dell notifier live?

-- 
Pali Rohár
pali.rohar@gmail.com