Re: [PATCH_v7 2/2] ACPI/IPMI: Add the IPMI opregion driver to enable ACPI to access BMC controller

[ykzhao <yakui.zhao@intel.com>]

On Mon, 2010-07-19 at 22:54 +0800, Bjorn Helgaas wrote:
> On Sunday, July 18, 2010 07:52:28 pm ykzhao wrote:
> > On Sat, 2010-07-17 at 00:01 +0800, Bjorn Helgaas wrote:
> > > On Thursday, July 15, 2010 08:34:35 pm ykzhao wrote:
> > > > On Fri, 2010-07-16 at 00:27 +0800, Bjorn Helgaas wrote:
> > > > > The ACPI IPMI opregion code deals with an ACPI device, and the
> > > > > obvious place where you have that device is the driver "add"
> > > > > function, i.e., ipmi_pnp_probe().  That's the point where the
> > > > > PNP core will help you out by matching device IDs and handling
> > > > > hotplug for you.
> ...
> > > > Yes. The hotplug scenario should be considered. This will be handled
> > > > under two places:
> > > >    a. the IPMI pnp detection: 
> > > >    b. install opregion handle for the hotplug IPI0001 device
> > > > 
> > > > But in fact the acpi_pnp device is enumerated only once at the boot
> > > > time.
> > > 
> > > Drivers cannot rely on anything like "the acpi_pnp device is
> > > enumerated only once at boot-time."  Device enumeration happens
> > > in the ACPI core and PNP core, not in drivers, and drivers can't
> > > assume anything about when it happens.
> > 
> > Yes. But in fact the ACPI pnp device is enumerated only once at the
> > boot time.
> 
> NO!  You can NOT assume the ACPI PNP device is enumerated once at
> boot time.
> 
> That may be the way the current implementation behaves, but the
> driver interface does not specify that, and it is likely to change.

Ok. I will try to use the hook to implement it.

thanks.
	Yakui
> 
> Bjorn

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