Re: [PATCH v2 0/7] ACPI: Add _OST support for ACPI hotplug

[Shuah Khan <shuahkhan@gmail.com>]

On Tue, 2012-05-08 at 14:12 -0600, Toshi Kani wrote:
> This patchset supports ACPI OSPM Status Indication (_OST) method for
> ACPI CPU/memory/container hotplug operations and sysfs eject. After
> ACPI hotplug operation has completed, OSPM calls _OST to indicate the
> status of the operation to the platform. If _OST is not present, this
> patchset has no effect on the platform.
> 
> This _OST support can be enabled or disabled with a new config option
> CONFIG_ACPI_HOTPLUG_OST. This option is disabled by default. When
> this option is disabled, this patchset has no effect on the platform.
> 
> The _OST definition can be found in section 6.3.5 of ACPI 5.0 spec.
> The HPPF spec below also describes hotplug flows with _OST.
> 
>   DIG64 Hot-Plug & Partitioning Flow (HPPF) Specification R1.0
>   http://www.dig64.org/home/DIG64_HPPF_R1_0.pdf
> 
> The changes have been tested with simulated _OST methods.
> 
> v2:
>  - Added CONFIG_ACPI_HOTPLUG_OST option. 
>  - Added _OST support for container hotplug and sysfs eject.
>  - Reordered patchset to enable _OST support bit of _OSC in the 
>    last patch.
> 
> ---
> Toshi Kani (7):
>  ACPI: Add CONFIG_HOTPLUG_OST option
>  ACPI: Add an interface to evaluate _OST
>  ACPI: Add _OST support for sysfs eject
>  ACPI: Add _OST support for ACPI CPU hotplug
>  ACPI: Add _OST support for ACPI memory hotplug
>  ACPI: Add _OST support for ACPI container hotplug
>  ACPI: Set hotplug _OST support bit to _OSC
> 

Did you look into implementing this maybe in a generic way by adding a
new device_ops that adds the ability to return status back to firmware?
It can be left null on systems that don't implement _OST. This way it
might be cleaner and can extend to other means of returning status back
to firmware if any.

Adding _OST support the way it is done in this patch set is rather
invasive and CONFIG_HOTPLUG_OST only helps disable just the evaluation
of _OST method. Other code changes do get executed on all platforms.

-- Shuah