Re: [PATCH 13/13] ACPI: use unique number as bus_id of ACPI device in sysfs

[Zhang Rui <rui.zhang@intel.com>]

> > Also, the ACPI spec has some pre-defined root name-spaces, and I think
> > it makes sense to look up the device name against a small table of
> > those reserved names and print something more interesting than
> > a number.
> > 
> > eg. 
> > _SB	system_bus
> > _PR processors
> > _TZ thermal_zones
> > _SI system_indicators
> > _GPE events
> > 
> Yeah. I can do that. But few devices can benefit from this. :(.
> 
> 
> BTW: Maybe I can generate a patch to get the following result:
> Five devices with the fixed name shown above if they are declared in the
> BIOS
> And add a prefix for every devices, the prefix is one of fixed names,
> _SB _PR _TZ _SI _GPE. So devices are shown like _SB:dev001, _TZ:dev001,
> _PR:dev033 etc.
> But does this make sense? :(
> 
> The best way is to define a unique and meaning rule to name all the ACPI
> devices. Unfortunately we haven't reached an agreement until now, but I
> think we can leave this for further discussion.

Another way to fix this naming problem.
Many devices in ACPI namespace is meaningless. Only the devices with a
PNPID are physical devices and should be exported to userspace.
So we can only register these devices and use "PNPID:instance no" as its
name.
Add instance_no in struct acpi_device. Every time we fail to register an
ACPI device and get an error of "-EEXIST", loop acpi_device_list to get
the right instance_no and register again.

Thanks,
Ray