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    SubjectRe: [PATCH v3 01/15] ACPI: Add support for device specific properties
    Date
    On Wednesday 01 October 2014 04:08:56 Rafael J. Wysocki wrote:
    > From: Mika Westerberg <mika.westerberg@linux.intel.com>
    >
    > Device Tree is used in many embedded systems to describe the system
    > configuration to the OS. It supports attaching properties or name-value
    > pairs to the devices it describe. With these properties one can pass
    > additional information to the drivers that would not be available
    > otherwise.
    >
    > ACPI is another configuration mechanism (among other things) typically
    > seen, but not limited to, x86 machines. ACPI allows passing arbitrary
    > data from methods but there has not been mechanism equivalent to Device
    > Tree until the introduction of _DSD in the recent publication of the
    > ACPI 5.1 specification.
    >
    > In order to facilitate ACPI usage in systems where Device Tree is
    > typically used, it would be beneficial to standardize a way to retrieve
    > Device Tree style properties from ACPI devices, which is what we do in
    > this patch.
    >
    > If a given device described in ACPI namespace wants to export properties it
    > must implement _DSD method (Device Specific Data, introduced with ACPI 5.1)
    > that returns the properties in a package of packages. For example:
    >
    > Name (_DSD, Package () {
    > ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
    > Package () {
    > Package () {"name1", <VALUE1>},
    > Package () {"name2", <VALUE2>},
    > ...
    > }
    > })
    >
    > The UUID reserved for properties is daffd814-6eba-4d8c-8a91-bc9bbf4aa301
    > and is documented in the ACPI 5.1 companion document called "_DSD
    > Implementation Guide" [1], [2].
    >
    > We add several helper functions that can be used to extract these
    > properties and convert them to different Linux data types.
    >
    > The ultimate goal is that we only have one device property API that
    > retrieves the requested properties from Device Tree or from ACPI
    > transparent to the caller.
    >
    > [1] http://www.uefi.org/sites/default/files/resources/_DSD-implementation-guide-toplevel.htm
    > [2] http://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf
    >
    > Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
    > Reviewed-by: Josh Triplett <josh@joshtriplett.org>
    > Signed-off-by: Darren Hart <dvhart@linux.intel.com>
    > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    > Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
    > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    >

    Looks good to me.

    Acked-by: Arnd Bergmann <arnd@arndb.de>


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